Security: Locking doors 24/7 vs leaving building open to public

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I run a mix use building with residential on upper floors, retail stores on 2nd and offices on 3rd and 4th. Currently the building is open to the public on weekdays and Locked at night and on weekends. I am planning to lock it every day. We have issues of homeless and drug users wandering into the building constantly. They do drugs, lock themselves in the bathroom and do various things in the stairwell. The building lacks CCTV cameras and we don't have a doorman. I'm getting major pushback to lock doors everyday because the businesses fear customers will get deterred from a locked door. I plan to put up clear signage, directories and instructions to operate the intercom. But seriously I'm not convinced people can be that lazy or lack common sense to buzz the business to let them in. Anyone else have experience in this and how to appease these people. As if security and safety of themselves and customers are more paramount then affecting foot traffic. Thank You