It doesn't have to be for technical projects, but could be for a plumber or electrician.
The interview includes process questions, asking about certifications, and other factors like years in business, licensed & bonded, uniforms, or other specific concerns.
For software though, imagine freelancer.com, but there's an agent actively soliciting feedback, not just a one-time post and nothing happens (or someone else gets picked).
The rejection reply could still have useful info, like "We chose X instead based on their [experience, number of ratings, answers to questions like Y, Z]. Thank-you for your response to our request!"
Working for a big company in the US is massively underrated. Over time, most people working in these companies will be much better off financially and with less stress/health issues.
The silicon valley/tech bubble over-romanticizes entrepreneurship without realizing its NOT for everyone.
For every 1 success story you hear about entrepreneurship, there are 50-100 that fail. The stress and anxiety is not something everyone can or should take if they have the opportunity to coast at FAANG and make $500K+.
How many businesses make $500K in revenue in the US? Not many? [1]
I am paraphrasing here, but I really agree with how Scott Galloway put it: The US corporation is the greatest wealth creating vehicle in history. Way safer and easier to build wealth working at Google.
Giving "StArt a BusZineaSs BRO" as a blanket advice is very disingenuous.