PLA isn't really biodegradable though, requires specific compost facilities to process. You can see people's 3D printed junk last for years and years outside in the sun.Theres biodegradeable polymers like polylactic acid (PLA). But the name is a bit politically sensitive. No problem in China though.
Plastic straws are also uniquely flexible, which makes storage and packaging a breeze when compared against alternative which are usually brittle.
Ultimately this fight over packaging is just green washing. There are far more environmentally damaging things that humans do (illegal crude refining in third world countries for example) than some straws.