Who has the financial incentive to build charging stations? Both out and back and point to point operators will build charging infrastructure at their own hubs/terminals and use them for themselves.

You might see truck stops adding "public" chargers after that EV trucks become commonplace (in the same way that truck stops have fuel discount programs for member fleets) but how will EV trucks going to become commonplace if private operators using their own infrastructure are 99.99% of users?

Truck stops are thin margin. I don't see them making the investment without a need. Maybe if a big player (e.g. Swift, Walmart, etc) wants to convert to EV and kicks in a bunch of money to have their fuel partner make the capital investment. But I don't think that's going to happen until EVs are so good that it's a "profitably without nearly any doubt" type investment. You'll probably need to see a decade or two of short haul EV trucks and the accompanying refinement before that happens.