Opal we are not talking about 'travelling' as in 'for holidays. It is about people from a group of friendly nations being able to go and look for work for 3 months - without tons of paperwork. The fact is, with EU rules, the 3 months is the rules. For all sorts of reasons, which had nothing to do with the EU- the UK CHOSE not to enforce it.
When I came to work in the UK in 1970, pre EU - I had to have a post in place, with a work permit, and the firm wanting to employ me had to go through the hoops to show that they could not employ a local, but had to bring me in. I was so lucky as I knew the right people, with long arms- who were gently pressured to do all that for me. Exceptional and very un-usual. When we fell in love, the only way we could be together, was to get married- or I could not have stayed in the UK after my contract expired, I was just 19. Again how lucky we are that we are still together 49 years later.