Visiting a Terran colony world is not just a matter of catching a ride and going for a visit - like catching a bus, train or plane within your country.
Colonies in a way need to treated like other countries, and citizens of the owner country must apply for travel visas to them if going fora holiday or work permits for commercial or employment reasons.
Colonial resources are limited and they are tailored to cope with a certain visitor load. Also travelers often have to go through vaccinations and often quarantine requirements because of the alien biospheres of these colonies.
Casual visits are often not viable. Tramp merchant starships and even private starships are forced to dock with orbital stations and most often aren;t allowed to land on the surface without the crew obtained visas, having vaccination and going through a mandatory quarantine, including a decontamination of their ship if it has to land.
Most commercial starlines operate their quarantine and decontamination processes while on route and have onboard a certified doctor to take care of any issues and certify the starship or its ancillary shuttles with cargo and passengers cleared for landing at a ground starport customs facility.
Some private operators recruit certified doctor and implement similar procedures. This is most often done by corporate operators and they have expedited visa application processes.