I honestly don't see how some people cannot carry some sort of balance.
I have to say that I don't understand how people could NOT have credit cards, unless they have at least $1500-2000 in the bank at all times. If they own a pet, car, or house, what do they do when there's an emergency?
I am one who is not credit card free but pays off in full each month. One trick I learned early in my credit card days was to deduct the amount of the purchase on my credit card right out of my checkbook. That way it was there (albeit hiding) at the end of the month because it had already been accounted for. If I couldn't do that, I didn't need what I was buying.
As for an emergency fund, that I do have. It's 6 months of living expenses...I think most financial experts say to have 3 but being a single parent with a house payment, a pet, and my first new car in 10 years in this economy, I prefer to err on the side of caution.
I've managed to build this up by having a savings strategy and by putting all "found" money into savings. By found money I mean things like birthday checks, tax returns (thought mostly I owe a small amount rather than use the IRS as an interest-free holding tank), portions of pay raises, bonuses, etc.
When I was just out of college, you are right, I didn't have an emergency fund and could have used the credit cards to make sure I had the short term solution. But I also focused on the long term solution and now, at age 40, I am in a good position. I am certainly not rich but should anything happen, I have a spending and saving pattern that won't make things worse.