It is 100% going to be easy to get visa if you have a ticket.
You have no idea about the US visa system. A few years back, my B1 visa was put on hold for 6 months, just because of some administrative formalities. And many of my friends have faced difficulties with different types of visa. If you are a citizen of some of the developed nations, then it is relatively easy for you to get your hands on a US visa. But if you are from countries such as India and Pakistan, then it takes a lot of background checks and additional verifications to get a visa approved. In short, having a valid ticket doesn't guarantee you a US visa.
you are very right - I agree with you! It not easy to achieve the US visa and there are so many things which can hinder in you and your USA visa.
Things will be very difficult when it will be USA and Canadian visa.
That is expected because not everyone can or is allowed to enter their countries without such valid reasons or proper requirements. Also, even if there are some requirements laid for almost everyone, it is still not that easy to acquire it because there are still other factors that they should consider before giving the visa. Especially if you're someone from the third world country.
For any country there are some rules when you want to take a visa and visit that country, that's the same for America, Canada, and many other countries. But in some cases, including America, they will make harder rules to make sure about the visitors who come to this country to make their people safe, I think even with all these hard rules they have, still, America will make some changes and allow people from all over the world to visit this country to watch the world cup games.