I have seen a few, most begin with F5. But then there are some I hve seen that involve multiple runners who thought a fly ball would not be caught.

I have no clue. This was in 1999.

3 weeks ago, had only my 2nd TP of my career. R2, R3 - F9 diving catch running toward 2nd base. R2 is complete dead meat, but R3 stayed by the bag, took off for home on the throw to 2nd and was nailed by an eyelash.

I'm barely into my second year of umpiring, and I've this afternoon's game featured the SECOND triple play I've umpired.

Bottom of the 2nd. First two pitches are bunt singles, 3rd pitch (both runners attempting to steal) is a fly ball to short center, caught by the center fielder (1), thrown to 2nd baseman (2), relayed to the first baseman (3).

My first triple play was in a coed slow pitch game last summer. 1st and 2nd, sharp grounder to short. R2 freezes on the base. SS fields the ball, tags R2, steps on 2nd, throws to 1st.

Probably won't see another triple play for at least a decade.

You see more when you're starting out because there are more at lower levels of play (where you usually umpire when you are newer).

... because the runners are less experienced and make more mistakes, allowing the defense to play on them.

....and the fielders are inexperienced as the coaches and parents jump up and down and yell and scream, "THROW THE BALL TO FIRST! THROW THE BALL!" :p

Your point, though true enough, lacks explanatory power. :p