Society didn't ban doing it, but put up barriers that help the average person from doing something dangerous.
It doesn't mean one can't buy nice things because one is afraid of being robbed.
The Play Store's scanning is very far from perfect, and the amount of crap that's on it, combined with the trust that people have towards it, and apps' unfettered access to internet, makes malicious software easily more common than on PCs.
Even without considering as malicious the enormous data collection that almost everything on the Play Store does, encouraged by Google