I don’t think it does. Their is a difference between leak proof and water tight.
For the former their are lots of solutions without such as paper and treated paper without going into advanced bioplastics and biodegradable plastics. These may still have advantages but their is a way forward, and they are probably the more dangerous form of plastic. But this feels to me like we’ve got lots of option and we are seeking to make them cheaper and better.
For the water tight ones, so for bottle and liquid good that might have to be stored for months or even years it more tricky. Making them biodegradable essentially means you need to make them permeable which kinda defeats the purpose. So this feel like more of a technological challenge. Maybe we just need to find the sweet spot between durability and biodegradability, I’ve had a single use PLA cup and PLA cutlery which was very good for the short use I had with it but is that good enough for mid a long term storage, I don’t know. From what I’ve read it can last a few months to a few years in a human body so maybe.
We pay for our paper bags to.