Why are public toilet seats "U" shaped, and toilet seats at home are ring shaped?

Question

Only thing I can guess is that most public means rooms have urinals, so you shouldn't normally be peeing standing up into a public toilet, so there is no need to lift the seat, so it doesn't need to complete ring shape to be able to lift up.

Answer 1

Toilet seats with a "break" in the front are called "open front" seats. The open front toilet seats afford the users more sanitary conditions and a greater sense of comfort than their residential closed-front cousins. The reason that the open front toilet seats are so widely used in the U.S. is due to section 409.2.2 of the Uniform Plumbing Code. The Uniform Plumbing Code is written and maintained by the International Association of Plumbing and Mechanical Officials. The code has been adapted into law, in whole or part, by most of the United States.

Answer 2

I was hoping it's an STD prevention. You can catch stuff from under the toilet seats. If there is no seat there, you don't have to make the extra effort to not touch it.
But no, it's to keep people from spraying the seat
http://www.straightdope.com/classics/a4_006.html

Answer 3

That way people don't pee on the seats, but they have urinals for that. I don't know.

Answer 4

less piss on the seats