Except that most people are fucking selfish. As indicated by your own response focusing on the individual instead of society.Exactly. But no need to ban people who are not sick from travelling.
I have several first world friends, even a family member who travelled when they had COVID symptoms. My family member even said that he didn't want to take a COVID test in case he was positive,because he was going home no matter what. I never bothered to ask if he even thought about the other people on the plane...because I knew the answer.
Now... let's think what a Chinese person would do if they had the chance to come to Canada. They were just released from government ordered self-capitivity, living in a city/province with 90% infection rate and effectively NO healthcare and they get a cough in the taxi on the way to the airport?
Travel restrictions aren't an all or nothing-zero risk 100% efficacy thing. They are to slow the transmission into the region.