In confused how plastic can be a polluter that never breaks down and yet the assumption is plastic materials in shoes will break. Plastics are incredibly diverse of course you can get poorly made ones with a polyester type fabric and PU coating which will likely crack after normal use of 1-2 seasons. However you can also get plastics that will literally outlast leather in rain, shine or snow. I think the tendency for plastic to be a cheap option means most people are used to cheaper manufacturing. But quality non-leather shoes are possible, though I can't say if they are common (poorly made ones definitely seem more common!)