M.J.
First child, our son, took over a year to train (started at two and a half). He had no interest, no motivation, nothing. We bought the "potty train in a day" books, did potty parties, rewards, you name it. We finally forced the issue when he was the last in his daycare class to move to the preschool room when he was over three. Put him in underwear and dealt with lots of laundry and lots of cleaning for days and then he got it. However, he had frequent accidents a good year or two after (into kindergarten and once or twice in first grade). We joked for a while he'd be wearing pull-ups to his prom. I honestly think he'd still be in pull-ups at age seven if we left it up to him. He still waits until the last minute to go use the potty.
With our second child, our daughter, we had zero motivation to train and planned to put it off. However, she mentioned she wanted to use the potty at two. We decided to follow her lead, put her in panties and she was accident free within a month or two and remains accident-free at four. Piece of cake. No potty parties, rewards charts, games.
In both cases, daycare was consistent with what we were doing at home. The move from pull-ups to underwear was key.