If there were some way to assure people it only did what they say it does, and couldn't be modified in the future, I wouldn't really have a problem with it (bars are public places; at the very least, getting person-counts would be good).

Maybe they could skip the gender and individual profiling and do low-resolution IR, which would be a pretty decent way to identify human-shaped blobs. If you monitor entrances, you could assume no one dematerializes inside, so starting from zero, just count people who enter and leave to get a count.