It was a (unhidden ?) stealth tax. If the concern was the pollution they'd have banned plastic bags, but they didn't, they demanded money for them.
As for Emma, whether the criticism is warranted or not, if one lectures not to do something and then does it oneself, one can expect to be called on it.
Doesn't mean we're not taking the underlying issue seriously; well those of us not virtue signalling and causing problems for society by causing a nuisance and obstructing for days while the police allow it, anyway.