I was hired (W2) by a staffing firm to fill a role. I interviewed with the client where I would be doing the work, and was offered the contract position. As part of the onboarding process with the staffing firm, I was then asked for references which they checked.
I wonder what would have happened if my references didn't check out. Would they then inform the customer that I wasn't available? Would they turn their back on almost a $100,000 in revenue (the portion they would take from my contract)?
I've been a software developer for 20+ years, and almost all of my work has been on things I can't show to potential employers. Tell a story about how you made an impact, use screenshots or video to supplement, but don't try to "prove" anything. If they don't believe you, then you don't want to work there or you need to get better at telling your story.
(This doesn't apply to designers, or people trying to get a job based on UIs they've created.)
Other markets like NYSE and NASDAQ have circuit breakers. If an index declines by a certain amount, all trading is halted so people can think and sort out their positions. This doesn't stop a single stock from flash crashing, but transactions during a flash crash are frequently reversed.
It's the new name for a home screen bookmark.