Well, those three incidents aren't what I described.
I can believe Ranma would let someone get a power up in front of him, confidant that he could handle the opponent anyways. (Which, natrually, he wouldn't)
While those three arcs are had different circumstances. Ryoga wanted Ranma to remove the Mark of the Gods, because it looked so stupid. Ranma never really made a judgement on Ryoga getting the power up or not. While the Super Soba and Battle Dogi were Akane getting the power ups, and then Ranma getting jealous afterwords for not getting them, and working to try and take them away from her.
He was never in a position to do anything about them and his relationships with Ryoga and Akane give different context to them anyways.