Do colleges generally need proof of ECs? For example, I volunteered at an organization for two years, and it’s not significant enough to be one of my letter of recs but I still want to include it on my application. How would I prove that I actually did this? Otherwise, couldn’t people just lie about some of their ECs?
Colleges will not expect proof with the application. They will 99% not ask for proof at any time. The most meaningful ECs can be easily googled, if an AO so desires. And your important ECs will likely be mentioned in on of your recs.