Why do you have to visit 3 countries?, I think if you intend to watch the world cup matches live because your country's national team will play, just look at the group phase where your country will be based camp, after that if they can advance to the next round then the United States is the choice because this country has a larger portion of organizing matches than the other two countries, but if you don't have the funds for that then it's actually not a problem because matches will always be broadcast live and that's enough in my opinion because I will like that too.
That is not a fair argument. There are millions of football fans around the world, who want to watch the world cup matches in person rather than on television. And conducting the tournament in three countries instead of one complicates things for them. The last time world cup was co-hosted was in 2002, when the matches were staged in Japan and South Korea. Even then, the distance between venues were manageable. But that is not the case with USA and Canada. Boston to San Francisco is close to 5,000 km and even by air it will take 6-7 hours. And then there are visa requirements to travel in the US. Getting a US visa can be very difficult.
I think for events in these 3 countries of course the participating countries will provide convenience whether it's visa requirements during the world cup, so there's no problem for that anyway if everything is complicated then it won't be held for this world cup event in 3 countries, it's just In my opinion, it is impossible for the organizers to make complicated permits and requirements for world cup spectators.
So there's no need to worry about permits and visa requirements because of course FIFA will also prepare easy access for spectators to enjoy this world cup event which is being held in 3 countries at once.