I have copies of their drivers licenses and socials.

I am a truck driver by trade currently, and do some different forms of e-commerce for a side hustle in the mean time. 

So far I have never ask a person or entity for their SSN or Tax ID, only their drivers license # and all vehicles' license plate #s  *unless* IRS indicates I must in writing.

Reminds me of the "good driver" and "multi-policy" discounts given by the insurance companies.The difficulty I see is how well the screening tools you use will give you a definitive answer about the applicant's background and status.

Also, ask them for their IDs and write down the address - they'll think you're writing down the driver's license number. 

Because of that, I'd probably even accept a CAN drivers license and proof of income (ie, CAN rent roll if you plan to live off that til u work in USA).

maybe requiring the original SS card (or an original certificate from SSA for originals lost) will help weed out illegal residents in CA where we are not allowed to discriminate between citizens vs non-citizen residents nor make unreasonable demands for documentation ie ask a person with a strong accent for a passport in addition to their driver's license when we just accept a driver's license (or combination of driver's license and SSN as 'two forms of official ID') from other applicants without a foreign accent or whatever?

If they have a fake SS# or Drivers License you won't be able to report them to credit agencies, take them to small claims court or many of the other things that we as landlords often use as leverage.  

Nothing too major surprisingly, but the driver and passenger fled the scene and were later caught.

As landlords, we need to be in the driver's seat at all times.