I think technically it’s both, but it’s mainly focused on the former - the shop and supermarket ones. You now pay 20 or 30p for them - previously when they were free, they would sometimes force a bag on you, even if you didn’t want one (I guess to walk around advertising their shop).
Here they still exist - they just make you pay if you want a new one. I (and seemingly most people) use them all the time still, but I guess more people reuse them more times now. I’m quite happy to pay 30p for one when the old ones get used up. I think they’re a bit sturdier than they used to be too - so less likely for the handles to snap when you’ve still got a mile to walk home.
I guess it mostly cut down on unwanted ones getting littered etc. Now they’re valuable, all the more reason to hoard them in a cupboard in the kitchen.
Where you are it sounds like they stopped existing - what do you put your food shopping in? Do you still have a thousand left that you previously hoarded?