Because nobody cares if a semi-unfit 47 year old is running at his top speed across 43 marathons.
The physical demands are also very different in terms of the twists, turns, sprints, fast stops that are required of the players. Never mind the recovery time after the usual bumps and bruises of an impact sport.
Mourinho's basic rule of thumb is that he wants three days between games. Day 1 - recovery, light training, massages, rest. Day 2 - training. Day 3 - light pre-match training/technical prep. And of course that assumes that we don't have travel/accommodation issues that disrupt the players' rest/sleep or their pre/post match food and warm up/down routines.
Hence he's not too fond of Thursday/Sunday or Wednesday/Saturday schedules. Presumably he's not that impressed by our New Years one of Saturday/Monday either. But at least everyone's in the same boat at this time of year.