Had it been my daughter who was a very easy child and very cafe friendly I would have said yes. Had it been my son aka Houdini I would have said no, no matter how happy he would be if sitting at a table.

I think it's all relative. I don't necessarily think she was being rude, just desperate by the sounds of it. I would have though, suggested the restaurant perhaps look into second hand high chairs to cater for all their clientele. That is who I would have been most disgruntled with.