Another parent here with a DC considering under-graduate studies in the US (or possibly Canada). Still at early stages, entering Y11 but her school try to start the students prep from Y10, to at least think about the areas of development needed for application. They had circa 60 international offers in 2019, most of which were North America so there's fortunately a robust system in place, should we pursue.
I tend not to discuss publicly, as US apps are often met with derisive comments in RL, such as do we have more money than sense; our DC's Head thinks it's now easier to get into Ivy than Oxbridge (she doesn't aspire to study at Oxbridge!); there are Liberal Arts degrees now in the UK etc etc. I'm not overly sensitive to it, as the reality is, it IS potentially expensive (especially with all the extras of flights, insurance, books, not being able to work outside of term other than on-campus jobs as part of visa rules). Even on full ride/scholarships/financial aid or whatever the support, there are extras that won't have been budgeted for with the same ease as studying in the UK.
Many of the DC applying from DD's school are from US parentage, but not all. There are colleges that have financial aid calculators that give a rough indicative figure to financial support which is useful start point. Also if from state school but nearly independents that have a strong US division, worth contacting them for outreach support, that includes being invited to US visiting college talks, transcript and SAT/ACT support, as ours and a neighbouring school provides locally.
The point about the varying standards of US students vs UK has been openly discussed by the various US visiting college talks we've attended. They really like British students that can make US students up their game, and our exam system is seen as a robust indicator of academic potential. They don''t mind if A levels of IB. The numbers nationally are still small from the UK, and being part of the wider international pool, if successful will still be out-weighted by American domestic undergrads. But if you are an all-rounder with no idea what you may want to do yet, enjoy participating in extra curricular stuff and are pretty sociable, then the US can be a more appealing place to study.
DD has ruled out anything but east coast due to travel times, prefers large, city type campus vs smaller, rural colleges, and if able to improve on her sport, will try and get on the radar for athlete recruit status. I don't know the answer to the T&Cs attached to a sports scholarship, once accepted, but I don't believe it's as rigid with athlete recruit status, albeit the expectation is to contribute to the sport across the 4 years.
Sorry that was long! In summary, if she knew what she wanted to do now such as specific industry/profession, I would recommend she sticks to UK as I do believe the degree quality is better here, but as she wants to remain as fluid as possible with interests across many subjects, the US, if successful may be better value and be a more enjoyable experience for her. She can always submit a UCAS application if she changes her mind, but would prefer to have an earlier US outcome if possible. It's also a lot of extra work, and unless she's prepared to manage her diary, relationships for teacher references, prep for SAT and so forth, there's no point in pursuing. I believe lots of applicants at her school drop out in Y12 when they realise how much extra work is needed.
Good luck to those going down this route!