With streetcar tracks if you hit them at about a 30 degree angle you can roll right over them. On a bike no matter what you got to constantly be scanning the road surface before you to watch for potholes, ruts, gravel and ice patches, puddles and whatever.

Usually I do a little bunny hop over street car tracks, and taking some time to learn these sorts of handling skills is very much worth the trouble if you intend to make a habit of commuting by bike.