Vegans and the Provisional Vegan Front
It's quite possible to wear leather on your way from the job killing bunnies as part of testing animal product-based cosmetics at the animal experimentation lab to your local fox hunt while being a vegan and a member of the Vegan society.
You might not be the most popular member, to put it mildly, but all you need to do is not eat animal products. (And pay the subscription...)
There are other vegans who extend that to trying to avoid all animal-based products. It's this bunch who are getting upset about the new fivers.
How they cope with the fact that a large proportion of plastics are derived from crude oil, otherwise known as the remains of lots and lots of plankton and amoebas etc, I don't know.
Perhaps some animals matter more than others to them, but it can be hard to see reality from the very top of the moral high ground.