Why??? Do they not use them?

You might try this, especially if you have room in a pack to keep them cool:
Take a bandana or two and fold each one to about 1-2" wide then end to end until it is folded up neatly to carry in a pocket or seat pack. Wet it thoroughly, squeeze out excess water just so it is not dripping (it should still be very wet), put it in a baggie, then put it in the freezer overnight. In the morning, put it in your seat pack and when you start to feel hot, take it out and it may be sufficiently thawed to tie around your neck.

I've used the almost-frozen wet bandana trick while gardening in hot weather and I was amazed at the difference it made. The air felt at least 10-15 degrees cooler and the coolness of the bandana lasted at least an hour.

I know, it's probably very Freddish..... but better Fred than dead (or dead tired).