This may not be uncommon in HSers who have these opportunities (and why wouldn’t one use their network to get an opportunity? This is what we tell students to do for internships and jobs), but nepotism/networks aren’t the sole way these students get research gigs.
Some HSs have programs with local universities for select students to do research, other HSers email local profs until they find one who will take them on, while others pay $$ for a uni research experience with a prof at one of the handful of companies that provide this service.
Interestingly Penn chose to highlight that 30% of Class of 2026 admits had academic research experience in high school. Most of these students are privileged to have been able to do research during a pandemic, but I have seen plenty of HSers hustle for the opportunity.
Research, shadowing and other clinical experiences are required for HS students who want to apply to combined/accelerated BSMD/DO/dental/PT programs.