You are correct, Jimmy, that Pikepass is not good in other states. It's very possible that someday Oklahoma's equipment will work elsewhere. I can't give you a time frame, however. There are a lot of details to be worked out before that can happen, involving equipment capabilities, cost, billing, and other factors. But it is being looked into, I hear.
As for other states using a transponder compatible with equipment other than their own ... yes, that is true.
In the northeast, for instance, there is E-ZPass. Last I saw, there were about 14 states using it. It does make it easier on the motorists, for sure. When you consider the number of drivers in that area, you can see that the process could allow a smoother traffic flow and save time.
It's easy to imagine the benefit. As I said, someday you'll probably see it here.
By the way ...
Another email I received said we shouldn't have toll roads anyway. The writer said states get enough money from taxes to pay for the roads and have no need of charging fees to drive routes around big cities and through light-population areas.
Personally, I don't ever want to see my taxes reach the level in our state that would be required to pay for all roadways' building and maintenance. It's a little more costly than he thinks.
Enjoy your week and drive safely.