[Neonlicht]

In fairness I think that these "locked doors" are to keep the homeless/drug users out or kids starting fires not really burglars.

[paxys]

Randomly press the intercom buttons until someone buzzes you in.

Wait 5 minutes for someone to come in or out (most likely a delivery driver) and tailgate behind them.

A locked building door is the weakest possible form of security. It isn't holding anyone back, whether kids or homeless or whoever else.