For all that people rail on about how stupid and illogical the credit score system is, it does generally seem to work in most cases. People who are financially responsible do tend to end up with good credit scores, and those who arn't tend to have bad ones.
The only area it's weak in is people who manage to get into their adult life without needing credit, but then if you've never had a car loan, a credit card, or any kind of debt, even if it's because you're financially well off, it's still probably a bad idea to hand you a 300k mortgage.
And building credit isn't hard. You don't have to pay interest, just get a no fee credit card, use it for some of your purchases and pay it off every month. Most banks will give you a credit card if you leave a deposit covering the limit with them for a certain amount of time, or you can get someone to co-sign (usually a parent).