Not really. Freight lines are usually built at-grade and occasionally intersect city streets. Caltrain tracks included. Some of the Caltrain stations doesn't even have elevated platforms.

It would be... unpopular... to have an electrified third rail, at ground level, that you have to step directly over at a station or running directly through a city street. Somebody would surely trip on it or it could get touched by a little kid.

Third rail systems are usually only used when the tracks are physically inaccessible to passengers or other pedestrians.