For me it's experience in the industry. If you can see my work history, that I have >25 years in the industry, working for mid and large size companies, and lots and lots of startups, why do I need to do something like a 2-pointer / heap / etc kind of problem to prove I can code?

One of my favorite job offers was literally a conversation that played out like: Manager: Cool, come to our office and meet the team Me: Want me to prep for a tech challenge or something? Manager: Nah, you were employed by ____ for __ years -- if you were incompetent, they would have fired you years ago.