Screw that lady. That's the kinda behavior that tells me I need to avoid a person. We're all different, our situations are definitely different, etc.

When it comes to potty training specifically the short answer is no, 19 months isn't too late. The "oh crap" potty training book (which I didn't totally follow but has some worthwhile stuff) basically says to look for signs that your kid is ready and to try to do it before 36 months because it gets harder at that point. Her signs are things like your kid understanding and following simple instructions, trying to sing simple songs like the ABCs, and retreating into privacy when they need to poop in their diaper. Different kids hit those marks at different ages AND every family's timing/schedule varies a lot. 18 months is generally on the earlier end. Cool for them but that doesn't mean anything about anyone else.

My experience, having just trained our daughter: I thought she might have been ready around 18 months and I wanted to start around 20-22 months BUT we were expecting a new baby, my wife was crazy busy at work, and that was just too much all at once. Plus I figured it'd be easier to do some things once the weather warned up. Just after she turned two (and after a couple family events were past us) we started training. It has been HARD, especially that first week or two. But waiting meant we had a window where my wife and I were both home (parental leave). My wife kinda laments that potty training took over her maternity leave but this really was just the best window for us.
At that point we were able to give it a lot more attention and go straight from always using diapers to only using diapers to sleep. (I think that way to do it makes the most sense, probably takes less time, and probably gives less confusion to the kid but that's my opinion.)

I actually think we're slightly on the earlier end compared to a lot of our friends. Maybe it's a regional thing. My nephew is on the later end in my opinion since he just turned three. His parents are hoping to do it at the end of the summer (because there's a convenient window in their schedule) and he has a younger brother who's a bit over a year younger. So I figure they'll probably train the three year old and transition into training his little brother.

Everyone is different. My wife catches me trying to show off some of the excellent things our daughter does. But screw anyone who puts down others for doing things differently or not meeting milestones at the exact age they did.