DS, on the other hand, was reliably dry during the day for a looong time before i would honestly say he was independent. i stopped diapering him when he was, i dunno, 22 months? but i would say it's only been about 6-8 months since he is truly independent in terms of always making it to the bathroom of his own initiative without accidents and without me reminding him (he'll be 4 in July). we spent the interim period between 22 months and 3.25 years doing a dance where sometimes i'd have to offer 100% of the time, sometimes he'd initiate 100% of the time, and most of the time we were somewhere in between, where he'd sometimes tell me but other times not and if i was relying too heavily on him to initiate we'd have a string of accidents and i'd have to pick up responsibility again more heavily for a while. he was doing really well until i got pregnant (just after he turned 2) and we had a horrible couple of months, and we didn't get totally back on track until after the baby was born (3 months before he turned 3). of course we mostly didn't have misses even during that time because i was offering. but whenever i didn't it was miss city and it was very frustrating.
it was really frustrating feeling like we were so close and yet not quite there. but i also am soooo thankful that we were EC'ing because i very firmly feel that he would've been one of those kids that would've been a nightmare to potty train and wouldn't have been out of diapers until at least 4 yo if we had done it how most westerners do. as it was he was, to the outside view, independent before age 2. and never did he have poop misses after the age of abouta 15 months. so i am really grateful for EC.
i think your perception might be skewed because your older two were easy to PT. #3 probably would've been challenging no matter what. he will get it eventually, for sure. he might just be telling you right now that he's not ready for the responsibility yet. at least, that's what i felt my DS was trying to communicate when he was doing the same thing.
hang in there!!