/mnt is meant for volumes that you manually mount temporarily. This used to be basically the only way to use removable media back in the day.
/media came to be when the automatic mounting of removable media became a fashionable thing.
And it’s kind of the same to this day. /media is understood to be managed by automounters and /mnt is what you’re supposed to mess with as a user.
Finland is basically “File a report if your income changes enough to affect your tax bracket. You’ll be issued a new taxation statement. Send it to the employer. (If unemployed, don’t bother, the agency who pays you already knows.) Your employer/the agency will send the taxes owed to us. You’ll be sent an annual tax proposal - If you have no deductions, you don’t need to do anything, if you do, then it gets mildly interesting. If you get tax returns, you don’t need to do anything if we have your bank details. If you owe us, oh boy, we’ll let you know, don’t worry.”