Do you tri- gals really have to carry tools and do your own repairs during a race? I've never done tri- only road racing and you don't carry anything extra. If you get a flat there is a wheel car and you'll get a change. If you have a worse mechanical you may not finish. During time trials there isn't even a wheel car, but the distance is often short enough that by the time you change your tire you'd may as well have just walked back so as far as I know no one bothers with the extra weight of tools and tubes.
The bike portion of IM(even 1/2 IM is longer than our state ITT championship) is pretty long so I can see the logic if there is no race support.