Well again, laugh tracks don't tell you when to laugh, they recreate the ambience of watching comedy with a group of other people as opposed to by yourself, since comedy is a communal experience and you're more likely to laugh at something funny in the company of others.
On kids shows, however, they're not utilized as efficiently as they are on primetime sitcoms, but that's something that's been going on since the late 60s: watch any Sid & Marty Krofft show, the laugh track is not only repetitive, but there's often laughter when there's nothing funny to laugh at. Then again, part of the problem then was that apparently audiences didn't really know how to react to puppets and people in foam rubber suits.