Why are Asian Massage Parlors always in public/shopping areas and do not get shut down immediately?

From what i’ve read about Asian Massage Parlor’s is that often, they offer sexual services for money. And i’ve also read about how the police goes after these places.

If that’s so, then why all the Asian Massage parlor’s in my city and other cities are in public areas with many shops around them, all out there in the open. Most people obviously know about them and know where they are. And they are usually open from 9am or something to late at night like 11 or 10 and the guys go in and out.

I don’t see police shutting down the place immediately when the store first starts business. If police cares so much about it, why do they let them be in business in the first place?