In principle I don't disagree with you; the US certainly had its share of purely bureaucratic boondoggles (e.g. Veterans' Affairs). And were it not for the TSA, our almost systematically acerbic customs officers, overbroad do-not-fly lists, the excessive systematic distrust placed on foreign visitors (e.g. by requiring visas even from close allies), and (most recently) travel bans designed to cut off families from each other, I would agree with you in this specific case. But these aren't just happenstance resulting from bureaucratic fumbling; these are conscious policy decisions.

We did after all just experience a national episode of confusion by a seemingly organic process (fake news) which turned out to be orchestrated by a foreign power for its own benefit. It's not unthinkable to me that (purely as an example) Russia also tilts public discourse in such a way as to make it politically untenable to dismantle, or even let stagnate, these self-destructive security apparatuses.

It's entirely possible the answer is very simply, "the xenophobic voter block really is so committed and influential." No conspiracy there, and that's a very useful answer. It tells us exactly where we need to focus our energy to fight these policies. I personally doubt that xenophobes are so educated about international travel as to pay sufficient attention to the workings of the visa system that it matters to them in the voting booth that Swedes need visas for nerd conferences, but I could very well just be biased.