Indeed; these teaser rates make money for the banks when most people who take them snap up to the higher rate (by error or simply keeping the balance after the promotional period).
It's best to only take them when you can set up an automatic monthly payment, and zero the balance before the higher normal rates return.
(Personally, I'd also make it illegal to advertise "0% for 12 months" if accompanied by "3% transaction fee" on the insider/fine-print. That makes the effective 12-month rate about 3%, which should be the headline. But banks, lotteries, and perhaps even government schools have an interest in keeping most people from being too good at time-value-of-money/expected-return calculations.)
It's best to only take them when you can set up an automatic monthly payment, and zero the balance before the higher normal rates return.
(Personally, I'd also make it illegal to advertise "0% for 12 months" if accompanied by "3% transaction fee" on the insider/fine-print. That makes the effective 12-month rate about 3%, which should be the headline. But banks, lotteries, and perhaps even government schools have an interest in keeping most people from being too good at time-value-of-money/expected-return calculations.)