One of the rationales of the single-use plastics ban adopted by the EP in 2019 was that it would spark innovation in cheap biodegradable recyclable plastics. Has any progress been registered in this regard?
Not sure if this question is suitable for this site but here's some (unsubstantiated by data) information and some other interesting points relating to economics behind it.
Rationale of the ban is not unfounded. It is based on a rather simple concept famously known as the Porter's Hypothesis. However, there is more economics at play (explained below). But that later
Coming to innovation: there is some evidence of innovation in biodegradable plastics. For example, in flights the plastic spoons/forks and knife given with packed food are now made of biodegradable plastic. Now the biodegradable plastic material is not even remotely as strong or malleable as regular plastic. But with right mechanics and design, the industry has finally been able to come up with usable (not necessarily affordable) cutlery. This we can definitely consider innovation.
But that is not all that is happening. One can certainly argue that if it were possible to make biodegradable plastic cutlery why did it not happen earlier? The simple answer is it was expensive. The biodegradable plastic cutlery is heavier compared to plastic counterpart and the raw material (which comes by weight) is also more expensive. It was because of regulation that industry was forced to take away from market the cheaper (and at that time - far better) alternative.
This is step one. Step two of the intended consequence is the new product becoming economical. So interestingly (unfortunately, I am unable to find the article now), the price of biodegradable plastic (usually corn byproduct or similar something) is increasingly becoming more affordable (economies of scale). The design is being copied and adopted by many take-away restaurants. So you see, perhaps in foreseeable future, even if the regulation is removed, industry may continue to keep using biodegradable products.
So if all goes well, it becomes a win-win in few years time.
As an economics student, what's of interest is that a pareto improvement outcome (an outcome which is favourable for some and not unfavourable for any) was just lying there. However, market outcomes are seemingly not that far-sighted and therefore often requires a nudge to set it moving in the right direction.
You can relate this to many things: fuel efficient car engines, battery driven cars, lending to small entrepreneurs and what not!