It's not just "lazy" parents. It's also parents who are totally paralysed by being told continually that they're doing everything wrong, and who are being bombarded with various potty training plans and schedules, and "signs they're ready", and who just don't know where to begin.
I know a lot of my friends were horrified that I took mine out of nappies "before they were ready" (around their second birthday). And yes, mine had quite a few accidents, and they weren't "done and dusted" in three days, or whatever the magic number is.
But in my experience, a few wet trousers is much easier to deal with than a 3.5/4yo who's become very resistant to making the change from nappies to toilet (and they're probably too big to be comfortable on a potty by this stage which doesn't help).