That's never been the standard at the border.
The starting assumption when crossing any[0] international border is that you don't have a right to enter the country, until you prove otherwise.
People from wealthy Western countries are generally used to just waving their passports and passing through, but that is not nor has it ever been some kind of automatic right. People are questioned and denied entry all the time, should they fail to satisfy the border official of their eligibility for entry under the exact terms of their visa (or the relevant visa waiver program).
I'm very sympathetic to the idea that border officials should have less discretion to deny people entry without very solid reasons, but if you start talking about 'innocent until proven guilty' at a border today, you're not going to have a good time.
[0] International agreements can of course modify this default assumption, e.g. Schengen.