"Unlike the bars or nightclubs many tourists may imagine, snack bars are warm, home-like places," said Mayuko Igarashi, president and director of Snack Yokocho Culture Inc, which has been offering tours of snack bars across Japan for travellers since 2021. "The 'mama'… welcomes guests with a sense of personal care."

I think it's pretty unlikely that they visit bars who don't want the tourists.

I often go on food tours in new cities (e.g. Secret Food Tours) and the restaurants they visit seem to like the consistent revenue stream during off-hours.

What's wrong with someone using an aspect of their culture to make a living?

"Exploiting" it means the mamas running the bar make more money... They're literally entrepreneurs. And if they don't want to serve foreigners they can always just have Japanese-only signage like many other places already do.