I have one where the cage might as well be off... It's missing 1/3 of the horizontal bars and all but one of the vertical ones are bent, broken or not in contact with the tank. I have filled it up and it seems to be fine. Someone told me that the cage is just for transportation. If that's actually true, I don't know.
A friend gave me one without the cage. I filled it 2/3 full of rainwater and put fish in it and it promptly bulged out and cracked horizontally mid way. So I built a wooden frame around it for support and put a plastic liner inside and still use it but it was damaged quite a lot. Guess they need that cage for support if holding liquid.
With appropriate microbes, minerals and organic matter, there is no need for pesticides or herbicides.
Yeah, I had the same thought. But to me they're way more valuable as mega compost bins and storage tanks that I can move around. I also don't think I could sell an industrial square pond to the keeper of aesthetic standards, who is also my better half.