"In the sky" does not mean "free from regulation."

End users of terminal equipment are still subject to the regulations of the state in which they are located.

The ITU Radio Regulations (via national legislation) create obligations on satellite operators to ensure that they do not cause harmful interference to other states' services or to violate those states' sovereignty.

You ban the importation of satellite dishes, and you don’t let Starlink build ground stations. You can still get around this, just like people still import drugs, but you can make it harder.

Try broadcasting on a licensed frequency without a license and find out... If the terminals were completely passive, finding smuggled terminals would be much harder.