Simple they don't go to the USA but to will go to Canada or Australia or even the UK.The bigger question is why will they choose Canada over USA. Better weather, more variety of women, wine, cars and drugs, more choice of universities with bigger names (they are not coming to study anyways) and better real estate.
Why will you like to live in Seattle like Vancouver, when you can live in sunny LA?
Why study at UBC when you can study at UCLA?
If one is buying prestige, no place shouts that out much more than USA.
Canada is a compromise. I doubt these folks are here to compromise. And certainly compromise is not why even Canada is reaching out to them.
Even rich Chinese send their kids to Canada with a view to get them a foot outside China. If a new passport is not what you want, the kingdom down south is a better bang for the buck. Unless... you cant just live there from some very personal reason. Those folks are not very common.
Canada and global south are kind of made for each other. Both are seeking compromises. Nothing wrong in it. Most of us are middle class folks and we middle class folks always compromise.
1) The reason is USA Colleges cost a lot 4-12 times of colleges cost in the above 3 countries, and US degrees are also not easy to graduate. America doesn't give these half bakes 1 yr 2 yr courses tailored for Lambdas or Immigration Fraud.
2) Most of the Middle East students are sponsored by the Crown Government or Billionaires doing charity. What I get from @Impatient Dankaroo is those beneficiaries are kids of single women. These women I assume are abandoned by their Husbands who as per shariat law marry and divorce multiple times over their life time or went to fight religious wars and are dead.
3) Those charity candidates or their sponsors will look for value for money. In these 3 countries college fee is cheaper, candidates can get a degree relatively easier, whereas one has to slog their ass*s to even get a par score in the USA.
The extravaganza good accommodation/cars I mentioned about is bought with normal 3-5 k pocket money given to these students by billionaires and the students spend it unlike a poor Lambda who parents have taken a loan or pawned his farm, which weighs the Lambda to scourge for food in foodbanks, live with 29 other kids in @navinball like houses.
The Oil Heirs, yes as you say are in Boston or Manhattan or choices places in California, or last London's buying the best of education and lifestyle, wine, women what not.