A tax is superior to a ban.
There are occasions when I buy something juicy.
A plastic bag is just the thing to keep my cloth bag from getting stained.
A small charge for a bag is worth it then.

Ban those bags and what could I do:
not buy the chicken?
Get blood all over my knapsack, other groceries, and down my back?
Use a paper bag and have the bottom fall out when it gets wet?
Buy a box of trash bags and use one of those? Do you think I would remember to carry one of those around with me?

Please push for the gently discouraging tax.