Originally Posted by
john11111111111
I have been looking through dozens of options, routes, covid regulations in multiple countries, just trying to even understand what is going on. For example how can Ireland and the UK sign up to a common travel area and then have completely different rules on who can enter that area?
The UK decides who can enter the UK and Ireland decides who can enter Ireland. Being admitted to the UK does not mean you would be admitted to Ireland, and vice versa, even if there are ways to cross the UK-Ireland border without coming into contact with authorities.
Every Schengen country has different rules on who may enter, yet one could enter Schengen country A and then travel to Schengen country B perfectly legally even though one might not be permitted to enter Schengen country B directly from outside Schengen.