If a clerk in England didn't say please and thank you to a customer who clearly didn't speak English, as a fellow customer standing behind them, I would be mildly angry on their behalf.
I very much appreciate that I'm treated as any other customer in Japan. It's surprising how much more you can pick out of the 'scripts' on each subsequent visit.

As for dolls and cartoon figures - almost everyone has one dangling from their phone (which makes for easy identification) and it's become a huge industry. The choice of mascots available is bewildering. Goodness knows how many billions of yen this whole business is worth. It seems natural to me that people will 'tag' their bags in the same way.

Remember, most Japanese love shopping. Most Japanese don’t have much room to store their purchases in/on. Therefore, things you can buy that don’t take up much room tend to be extremely popular.

In Europe, people buy tons of ornamental crap for their mantelpieces and shelves. It makes sense to have a figurine dangling from your bag instead.