While it's true that plastics recycling is mostly a joke, in most places, companies manufacturing plastics aren't required to bear the cost of recycling in the first place (i.e. there has been no attempt to internalize the externalities in the first place), so I'm not sure it's even possible to invoke plastics recycling as a counterexample.
If there had been a push to make plastics manufacturers bear the cost of recycling, then the fact that recycling doesn't adequately cover the full externalities might be an example of the problems with this process (certainly there is an incentive for companies to try to downplay the negative externalities resulting from their products if they will be forced to bear the cost of dealing with those externalities).
The real way to make this process work would probably just be to tax plastics heavily based on their negative externalities and use that money to dispose of them.
However, this would likely make goods using plastics prohibitively expensive for consumers, so it might be unpopular, but it would likely cause people to use alternative materials that are more expensive than plastics are currently, which would be beneficial.
Even if they only kept up with inflation, bottle deposits would be at least 25¢ today. The federal government should treat the microplastic tsunami like it did the hazard of drunk driving: tie federal highway funding to states adoption of universal plastic deposit laws.
Just my 50¢
[0] https://www.alternet.org/2005/10/the_hidden_life_of_garbage