The bio-degradable items won't degrade at the expected rate, as you say it's an industrial composting facility that's needed, but they _will_ degrade far, far, more readily and won't leave the environment strewn with microplastics. That's what we seek.

I've tested composting a couple of compostable nappies (aka diapers) in my under-used, low temperature, domestic compost bin. After about 3 years we emptied it out and there was no sign of the nappies at all.

If an animal eats the corn-starch (or whatever compostable type it is) cup then it's not going to be especially harmful to them. Moreover, it appears from what I've seen that the compostable materials will not retain mechanical integrity after a small time of exposure to weather, this is good too.

It's not all sunbeams though, we had a fairtrade chocolate bar for sale in our store that was wrapped entirely in compostable wrapping (with vegetable dye printing, etc.), the compostable "cellophane" wrap was incredible. Completely transparent, flexible, shiny. But [I believe] the humidity was too high and the wrap grew sticky before the shelf life of the chocolate [<1y] had come.

It mightn't be perfect but it's a good way better.