If we use the following definition of brainwashing, then what people do with their children could not be brainwashing.
Definition of brainwash:
Impose beliefs on somebody: to impose a set of usually political or religious beliefs on somebody by the use of various coercive methods of indoctrination, including destruction of the victim's prior beliefs
You'll notice that it says coercive methods of indoctrination, not just simple indoctrinations. And it says it destroys prior beliefs. Children are born without beliefs.
I know you're not the first person to bring this semantic quibble up, but I think it completely misses the point of the thread. The question is whether certain tactics in child-rearing are harmful; whether they meet the strict dictionary definition of "brainwashing" is largely irrelevant.
This argument reminds me of discussions I've seen about sexual assault that end up being a snipe hunt about the definition of "rape" (e.g. "there wasn't penetration, therefore it wasn't rape") to the point where the question of whether a particular act is harmful - whether or not it's technically "rape" - ends up being ignored.