"I'm sure some kids are ready at 18m. Just not the majority"
no. the majority of children in other countries have bowel control at 18 months old and are not just out of nappies and being EC'd, but choose when they wee. I worked in a kindergarten with a very young intake - out East. They had a few accidents, sure, but in a group of 20 2-3 year olds you'd expect maybe 1-2 accidents a day. It was something of a scandal amongst the teachers when a 20monther came in still in nappies....
UK/US kids are just trained later as a matter of parental choice - now. They weren't 30 years ago, and todays toddler is not physically different to the toddler of 30 years ago.
when you train, and what method you choose - is completely up to you of course.
the method the OP describes is EC - but probably by 18mo, if she persists, they'll be genuinely toilet trained. I certainly wouldn't be arsed with it, because you can do a week or two at 18mo to achieve the same effect - a child that chooses to wee on the loo/potty and is genuinely loo trained.
just because you have chosen not to do this, there is no need to allege that is impossible, or that others have in some way abused their child by doing this - in fact those people that have implied that need to get some perspective.
unless you consider the giving of chocolate buttons a form of abuse, no toddlers were harmed in the writing of this post