These include rent control, security deposit regulations, lease violations, late fees, eviction processes, barriers to entry (permits, licensing, etc.), and so on.What are your thoughts?

You dramatically reduce your prospective buyers by doing so.

I know permitted ADU can get its own address but how does non permitted unit get a separate address? 

Many PMs will put lockboxes because this way they can give codes to prospects or buyers agent representing a tenant might just give and get paid a commission without doing much work.

The seller has to work on something at the house that had an open permit because not up to code.

If you are doing specific types of transactions (flips, BRRRs, etc) in a specific market, you could also find the person doing similar deals to yours (leverage tax deeds, property records, permits etc.) and ask them.

So Permits?

Builders tend to follow population growth and in my city most of the building permits are headed towards the suburbs.

Are inspectors willing to walk through a prospective property and tell me the estimated cost of rehab before I place an offer? 

I can provide specific examples of prospects if needed to clarify my situation.Thank you!