I'm not sure I agree with that. I was undecided for 2 years (of the typical 4 at a US institution). It wasn't a problem and didn't cost me anything. Expecting an 18 year old to commit to a program seems a bit excessive (yes, we do it for professional programs like nursing and engineering - but not all students are the same, both of those programs have high wash-out rates, and at least with engineering, if you get a job doing other things).