Because we don't need one. Most of those other teams have to deal with sub freezing temperatures and, in some cases, snow for at least a portion of their season.
We lose numerous practices due to lightning. Having an IPF is an advantage no matter how you look at it.
They need an IPF ... The schedule is unorthodox anyways... As it stands the team is done with practice before noon... so they are not out there in the heat of the day anyways. If they had an IPF they could practice in the evening and if the weather is bad they can go inside.
As I understand the practice schedule, they practice early in the day because the rain storms and lightning strikes are less likely earlier. I thought it was done to minimize the amount of practices that might be cancelled???
But to your point, with an IPF they could move the practice times to later in the day and get the benefit of preparing the team in the "reasonable" heat. And when the weather doesn't cooperate, use the IPF to get out of storms or "extreme" heat.