She can still build them right? Maybe thats the balancing mechanic. A spawned tank moves across the stage faster than an infantry but is less powerful. EDIT: Regardless, that to me is as irrelevant as Ivysaur not taking extra damage from Charizard. Charizard never learning seismic toss in the game naturally, except through TM or move tutor. And if TM's are an acceptable category for "normal" but Sami using tanks isn't (even though she can build them just as much as any advanced wars reps) then you might as well tell me right now that you wouldn't have a canonical problem if they gave squirtle Rock tomb or rest in the next demo (since squirtle can learn those TMs).
And for the record, I have beaten on hard mode, Advanced Wars 1, 2, and DS.
I wouldn't have a problem with Squirtle getting Rock tomb. He absolutely can learn that TM, and he will use it just as effectively as a Mankey will.
Rest is already part of Jiggs' moveset, so that's the reason you don't want it on Squirtle, aside from the there's nothing wrong with it being on Squirtle. I wouldn't be very upset if Squirtle got rest, really..
Technically Sami can't build tanks just as much as any advanced wars rep, Colin can build more
Just because Sami can, doesn't mean she should though. In competitive advance wars the game is heavily geared towards use of infantry and artillery units. Sami is somewhere between mid and high tier, iirc, because her infantry units are good, and they synergize with her artillery (her artillery does as much damage as any other CO's. Her tanks do less damage than normal CO tanks). And when you elect to use Sami in War Room and Campaign, you generally pick her for situations that call for little to no tanks.
I get that tanks are sort of a flagship for the series, but it would really bug me if she came out and half of her moveset was focused on the 18% of all unit types in the game that she is the worst at using. Excuse the hyperbole, but it'd be like releasing Charizard with half his moveset based on Hidden Power (water). Yes, technically, that is something that can be done, but you celebrate a character's strengths, not its weaknesses.