Peoples' "authentic life" is finding a job, finding housing, finding a school for the kids, interacting with neighbors, dealing with trash pickup and water bills, etc. A tourist can never experience that. Even if you experience the flooding with real Venetians, you're not going to deal with the water damage for weeks afterward, or attempting to get insurance claims paid. But that's "authentic life."
Charming restaurants, quirky bookshops, etc., that's not "authentic life." That's frivolity. Sharing frivolities with the locals doesn't give you any insight into their "authentic life." Tourism is always Disneyland. It's always fake. It's just different versions of Disneyland for people of different temperaments.
(It's funny you mention Bangkok. I was born in Bangkok. What exactly is less "authentic" about it than Venice? How can a city even be less "authentic" than another city?)