And what do you suppose the thought process was that led to the conclusion it should be 29 1/4 rather than 29?
You might be surprised how much thought goes into such things. There are published Architectural Standards for table and counter heights of all kinds, as well as for chair seats and backs, light switches, etc., etc., all based on average human dimensions.
Lots of pool halls have uneven floors where in order to be level the table surface is a different height from the floor at each corner, sometimes noticably. Some vary by more than 1 3/4 inches (31 - 29 1/4) so it's impossible to be regulation height all the way around.
pj
chgo