Why don't the HOMT tandem breakers fit into all Homeline load

Why don't the HOMT tandem breakers fit into all Homeline load two breakers in one slot a single tandem breaker That breaker slots or even replace two single slot breakers with a tandem breaker two slot toaster A tandem breaker is a breaker that provides two separate and different circuits in the same circuit breaker slot Said breaker slot can be completely regular-

two slot toaster Please see comment below for information on how to combine 2 Double Pull Breakers to free

two slot I have found double space and single space 20a breakers Other than taking half the room, the specs seem identical Both allow each half to be used as a One of the beautiful things about circuit breakers is that their size is standardized, so any breaker will fit in a standard breaker slot A