They don't just give the account to random people. It's always people with already some kind of social media presence, and stealing an account as well known as @Sweden is not something someone like that would just do.
tweetdeck (now owned by twitter) officially supports team access to twitter accounts. So you can add someone to the team account and let them tweet using the handle, and revoke the access a week later easily.
However, because tweetdeck isn't available on mobile devices, most of these rotated accounts end up using password sharing.