Well the Danish federal government covers the fiscal deficits with external debt , it's not too high i think is like a -1.7% or something like that but that is literally the definition of unsustainable , right now if a random brasilian or Argentinian kid applied for an extended VISA to Denmark , he'd get rejected in the blink of an eye , Denmark has very selective legal immigration , which makes all the refugee asylum programs all the more insane.
What i mean by vouchers system is : first off state run schools get fully abolished , demolished , erased from existence , then the federal government makes a braket of who are the poorest people who truly can't afford schooling , then the government pays it all for those people , all in the private sector , only from K through 12 , the middle and upper classes must pay their education out of their own pocket.
U.S colleges aren't as expensive as you might think , it's only the most prestigious ones , K-12 is mostly community funded , the majority of U.S Americans go state K-12 schooling.
Remember , the MOST IMPORTANT investment on kids and their education isn't at the college level , its from the ages of 3 to roughly 11 years of age , in an ideal world , the parents would send their kids to the absolute best Kindergarden and Elementary private schools , then for highschool let the kid choose , and then for college the kid can actually work or recieve a private voucher to go to a college of the field he actually wants to study.
Any country can go as free with immigration as it wants , but the only way to have sustainability when you expand immigration freedoms is drastically reducing state power , state goodies ("free" stuff) , subsidies and regulations , otherwise you're gonna be U.S , who's had literally the freest and most moral immigration system in the world period , and by a planetsize margin in the 1st world up until december of last year and they never cut expenditure , now they have a +20 trillion external debt NUKE waiting to explode.
It's fucked up when your countrymen already adopted the statist mentality dog....i don't think you can truly recover from that in like...99% of the cases.