Dawg, if you want to identify what makes the US perform worse than the countries ahead of it, it makes sense to identify ways in which it differs significantly from most of them. So, for example, teachers unions wouldn't be a good candidate, since unionization among teachers is a common feature of most of the countries that outperform us. Finland, for example, has a powerful teacher's union, and yet also dominates in the performance rankings. Similarly, smartphones are a poor candidate for the culprit -- most of the top ranking countries have high smartphone ownership, including Finland (home to Nokia, where 92% of people have mobile phones). The US is actually 83rd, internationally, in per capita mobile phone ownership. "Government teet [sic] suckers" are another lousy candidate for a culprit, since nearly all the countries that outrank us have more social spending per capita than we do, including the countries of Scandinavia, which are highly socialized, with social safety nets that put anything in the US to shame. I'd also argue that common core is a poor culprit, since it's recent and poor US rankings go back decades, and since most leading nations have something equivalent to common core (national curriculum guidelines, rather than high levels of local school district autonomy).
So, much of your list is just an attempt to push right-wing propaganda in a context where no sane person would think it's relevant. As for the items in your list I haven't already debunked, they may be worth looking into. It's quite possible our school administrators are overpaid relative to their foreign equivalents, and so we spend a lot of our educational money on things that don't directly impact what is happening in the classroom. One way to decrease that adminisrative expense would be consolidation of more administrative functions at a national level. When businesses merge, the biggest "synergy savings" are job cuts for middle-managers, since you can do more work with fewer people when you consolidate that way. In the same sense, if you had a single group of administrators building curricula, selecting texts, handling a lot of procurement, etc, at a national level, rather than reinventing the wheel in each of thousands of mostly-independent school districts, you could spend lesson administrators, overall.
Maybe single parent homes are a factor, too -- I haven't looked into how the US stands relative to those other countries on that front, but it makes sense that if a single parent is bearing all of the considerable burden of raising a child, he or she could not, on average, do as good a job minding the child's education. If so, we should look into what is driving the US's single parenthood higher than peer nations. Similarly, if you can show our kids are more "spoiled" than their international peers among leading countries, we should look into why that is. What are we doing differently to encourage that spoiled attitude?