I raised 3 children (so all were three at one time), and yes, we flew, but we *never* let them disrupt others lives. Were they perfect? Absolutely not, but with *consistent* discipline (not beatings, or abuse as some would love to call it) they learned their boundaries and what was expected of them. In fact, we usually didn't have to raise our voices, because we didn't throw out empty threats, but our *no* and *yes* meant just that.
They were happy children because they had boundaries and lots of love and interactions from us. They were not brow beaten.
Sorry, but I can't see the OP never had any problems with her child not wanting to ride in a car seat, or ride in a shopping cart, or whatever situation that required her to be restrained and behave herself. So, before her first plane ride she would have had a *clue* on what her behavior might be.
Also 2 kicks (the OP's words) would *not* make someone call over a FA. Would love to have the woman's *take* on this as well. Seems like from what the OP herself said that this was a *constant*. Why else fight with holding down her legs to *keep* her from kicking the seat??
And for those that say a 3 year old is not responsible or can not comprehend - sorry, from experience I will not buy that - if they are consistently shown their behavior they do know right from wrong.
Just coming back for WDW and being around so many children that the parents would not control, I wish I could have a $1 for all the *empty* threats and consequences given to children that the parent and child *knew* would not be carried out. Like one parent - "If you throw your new stuffed animal on the ground one more time, I'm returning it back to the gift shop" Duh! She did it, glaring at the mother who looked away. Another often heard, "If you don't quit whining, throwing a fit, we're going back to the hotel, right now." Duh, another empty threat!
Sorry, this is long, but I get sick and tired of children being excused for terrible behavior that's the parents fault.
So, no, I will not tolerate being kicked in the seat constantly on a long flight.
OP doesn't say anywhere that the woman *yelled* or *sneered* at her child as some have said. A *glare* is a hard look, and I've done that a few times in *ride lines* when I've been constantly bumped, kicked while the parents ignore, and most of the time the child quits - I tolerate it a long time and try to move out of the way, before the hard look though (this happened several times, but was especially bad with three girls about 4,6,8 in the TSM line. The Mom and g'mother were having a great time talking and ignoring them.