Flowers along highways.

In June my wife, daughter, and I took a road trip from Hanover, NH to Huntsville, AL. On the way we traveled nearly the length of Vermont and through parts of NY, PA, MD, WV, VA, and TN. Along the roadways we saw places that were profuse with wildflowers. Many of these areas appeared to have been deliberately seeded (I could be mistaken). Very Beautiful.
In Huntsville, while unloading the car I noticed the front of our car was covered with the remains of hundreds of insects. I could identify some as grasshoppers, butterflies, moths, dragonflies, wasps, and bees. Big fuzzy bees, blue bees, honey bees, little black bees, and others.
I had parked the car where we could see it from our second floor room. A short time later I saw a crew of about eight small birds working and pecking on the front of the car, some even appeared to be behind the grille. When we went out later that evening there were no identifiable insect parts on the car, just smudges and smears. I wonder now if our car was cleaned by birds at the four other motels that we stayed at on our way. While in Huntsville for several days we noticed birds cleaning cars in parking areas. This was our first road trip in the Eastern US.
Now, I think it isn't such a good idea to have so many flowers along highways.

I think it's a great idea to have flowers along the roadways. In fact, I have been known to deliberately plant perennial flowering plants along the road sides. Yes, I'm guilty of it and openly admit it. In New Jersey I propagated daylilies, azaleas, rhododendrons, forsythia, and daffodils. These now adorn the roadsides of that area. Here in Hawaii I mostly plant out food bearing plants (bananas, papayas), but also have planted pretty things such as spider lilies, ti plants, poinsettia, and marigolds. It's not only pretty and pleasing, it's beneficial.

All those varied insects on your car grill indicate a healthy ecosystem. It's not good to have few, if any, insects. I'm aware the urbanites think that zero bugs is good, but that's not truely the case. Do the wildflowers encourage insect populations? Of course. In my opinion, that's very good. It's part of permanent agriculture to have a good general ecology thriving nearby the farms. It supports to beneficial insects that farmers & gardeners want and need. It provides food for the birds, as you've discovered. Those birds also help control damaging insects in the fields and gardens. Yes some birds damage crops, but good farmers tend to accept that fact and employ practices to minimize the damage. Having a healthy insect population nearby actually tends to lower crop damage.

Those wildflowers very well may have been originally intentionally seeded. But they may continue on by natural reseeding. The fact that they are thriving signals a lack of herbicide use along the roads....very good. Where I live our county heavily uses herbicide along the roadways. But I've discovered that the road crews won't spray ti plants, a plant that has Hawaiian cultural significance. So I've planted stretches of ti plants along my own road, thus eliminating most of the herbicide use near me.

I think the OP is worrying that planting wildlfowers near a road has hastened the death of so many insects.  But still, if the flowers weren't there at all, there wouldn't be any insects to start with.  It would be more of a worry if lots of birds were being killed whilst feeding on the insects next to the road.

There has been a trend here for large municipal wildflower plantings on roundabouts etc as they are lower maintenance than mown grass or conventional annual bedding schemes.  There is also a tiny scurvy grass which has colonised our road edges from the coast because of the salt applied, which is a good thing because it covers the otherwise bare soil early in the year and holds back a bit more dirt from getting on the roads.  And this year, we had such a drought that the council didn't bother mowing a lot of verges round the town, and the yarrow being more drought tolerant got away like mad and flowered as it usually can't.  

Steve, I feel the benefits that pollinators, insects and birds receive outweighs the loss.  If wildflowers were not planted then the mowers would be killing them.

Here is an article that might offer some help in understanding:

https://www.fws.gov/southwest/es/Documents/R2ES/Pollinators/7-PollinatorsAndRoadsides_Guideline_Xerces_2014.pdf

Thank you Anne for showing the article on the benefits of planting flowers along roadways. I read the whole article. For less traveled slower roads like the ones in the article this makes a lot of sense.
We planned our trip from Hanover to Huntsville to take advantage of the quiet, slower, and less traveled routes. The relaxing byways through the idyllic countryside in the Eastern USA are wonderful. It took us a day longer and at least 200 miles more than if we had traveled the freeways the whole way. We did drive on busy state and interstate highways at some point each day though. It is these busy high speed highways with flowers planted along them that caused me to write my original post.
The amount of traffic on these main highways through the rural countryside really made an impression us (we are farmers from Idaho). There are thousands of vehicles traveling at a high rate of speed through many large fields of planted flowers each day. Flying insects, as well as walking, hopping, and crawling insects trying to cross these roads have a very high probability of not making it across alive. I wonder why people think it is a good idea to attract insects; pollinating and otherwise to these lethal killing grounds.