I'm sure it wouldn't be impossible to get a honey wagon at Roberts, Powelton, and Frazer yards, and cycle the equipment so that it sees one of these yards once in a 48 hour cycle for toilet servicing.
Other than St. Patrick's Day, New Years Eve, etc......you won't top off the holding tanks in a normal 48 hour equipment cycle.
The tricky part is weekend equipment that starts / ends at outlaying points like Media, Warminster, Norristown, etc.
On an MU, you are pretty hard pressed for space both in the coach, and under the floor for all the plumbing and hardware for a toilet compartment. On a coach, it's not too difficult. But now you have a fleet of passenger cars that are split between plumbing, and no plumbing.
Makes it confusing to Joe six-pack passenger.....The same person who led to the elimination of R-designations on trains, and express trains with names. We sure don't want the riding public to be any more confused.
The next concern is HAVE YOU RIDDEN A SEPTA LOCAL? How do you aim for the bowl when the train is accelerating and stopping hard every minute? This isn't like MBTA, Metra, or MARC where the train is running 70 or 80 miles with big distances between stations.