Doctors and their staff have an incentive to perform more procedures/tests because they get paid to do so. Because the patient often does not bear the full cost of procedures/testing, patients often do not do much diligence to see whether these are actually appropriate. While I don't think that the RN we were talking with was being malicious (surely her individual comp would not have been affected), I do think this is a symptom of a system with a principal-agent problem.
Of course, doctors can be an incredible source of information. But with all things, consider any potential conflicts of interest when taking advice.
And between kids. My daughter just up and decided at around 18 months or so that she was done with diapers and would use the big girl potty. Not one accident. My son was more apathetic about the whole thing, and it was sometime past his third birthday before he finally started using the toilet to poop in.
The piece of advice that stuck with me ... don't bother trying, they'll do it themselves when they're ready, and you probably can't accelerate it.
Take for example Vietnam, where kids are out of diapers at around 9 months[1]. Even in the US the age at which children are potty trained has crept up slowly from 1 year to 19 months to 27 months today:
> In the U.S., until the 1950s, most children were using the potty in the first few months of life and completely trained by age 1. In the 1970s, 18 months was an average age to start. Now, it's around 24 to 30 months.[2]
As the article asks, what are the phenomena causing these changes and what explains the huge discrepancies between countries and cultures? Clearly the biology of children does NOT explain the difference.
1. https://www.sciencedaily.com/releases/2013/01/130130082726.h...
Potty training is also something that differs widely between developed nations and rest of world.