[chimere]

That's right. The most common polar orbits, sun synchronous orbits (SSO), are actually inclined at ~97 deg from the equator. This means that they're moving slightly opposite of the earth's rotation, requiring it to be more than cancelled out.

This means that polar launches benefit a bit from launching closer to the poles where the Earth's surface velocity is lower. However, in reality the difficult logistics of building an arctic launch site mean that this is rarely done.

[emiliobumachar]

"rarely done"? Has it ever been done??

Searching for "polar launch" found nothing. (There's actually a Polar Satellite Launch Vehicle [1], but it does not launch from the poles [see Launch History at 1])

[1] https://en.wikipedia.org/wiki/Polar_Satellite_Launch_Vehicle