Up until 2004 you had to book a non-smoking rail-car in France. I remember having to book a seat in the smoking section because the non-smoking cars were full. Smoking was only being phased-out in high-school yards (for 15-18 yo highschoolers not only the staff)

Smoking on flights is less dangerous than lithium batteries. At least a cigarette fire can be seen and put out. A lithium battery in thermal runaway can explode and is not possible to extinguish as it is self-perpetuating.

The UK is the same as the US in this regard. It's quite a shock going to the continent. The most shocking for me was Germany. Regular suburbs up and down the country have vending machines selling cigarettes on every street corner. You don't have to walk more than a block from anywhere to buy cigarettes, 24 hours a day, it seems. What's more is they still have smoking establishments due to having an exception to the EU-wide smoking ban, because of course they do. I went to a smaller bar and didn't even know what was wrong at first, but something seemed different, then realised it was smoke which is at this point a distant memory in the UK.

They've mostly switched to vapes now. It's still annoying, but at least it doesn't leave trash all over the streets.

Seeing the sidewalks / parks outside of the main train station in Prague covered in cigarette butts as an American tourist in 2019 was certainly something.

Italy too. It's bizarre trying to hop on the trenitalia trains while a bunch of random people are standing on the platform right in front of the doors trying to get a few last drags in before the train leaves.

I'm not American though and while smokers are everywhere here, I don't recall ever being on a flight where smoking was allowed, even though the one mentioned was a connecting flight through Paris.