Mostly it is word of mouth on where to look for care too. Things like kijiji have a reputation as a place to search for what you need - including daycare so people go there. Since there are usually so many listings they can find several to choose from without going any further. Some of the other sites come up more by chance than routinely. If you type your city name childcare not all of those other places will be in the list so it depends on what terms the parents are using in the search box.