It’s quite possible that those local carriers are not equipped with ADS-B. If you’re seeing flight data with only a registration number and flight level, most likely that’s picking up a Mode S transponder signal, which only transmits altitude, in contrast to ADS-B, which transmits full position data.
The basic overview here is that ADS-B is still relatively new technology that’s far from being universally adopted at the moment.
If you are interested in tracking aircraft that don’t send ASD-B locations, take a look at www.planeplotter.com.
If there are enough users in your area, some of the a/c can be located.
I sent you a note in the messaging system. Click on messages in the upper left of the discussion board page.