Here (midwest US) it's stricter, at least in this city you can't do
your own work on a multi irrespective of whether you live in it.
People still do it of course. Being able to do your own pb makes
sense, as opposed to electrical, HVAC, load bearing stuff. You
probably can't run gas lines though that is technically a plumbing job.
Better safe than sorry vis-a-vis getting sued out the wazoo.