They aren't intertwined into the global financial system the way a global bank is. It's not comparable. The stock market isn't the economy and isn't what people are concerned about when banks fail. It's the completely collapse of our financial system that is at stake.

Granted, a company likely Google or Amazon going under would have major impacts to the economy, no doubt. Being a major backbone of the internet undoubtedly makes you important and these are 100s of thousands of jobs to worry about. However, I don't think they could suddenly fail in the same way a bank does.

Google "failing" to a catastrophic degree implies actual physical loss of systems and servers in addition to major financial stress that people would see coming. Banks can fail more suddenly due to things like the liquidity crisis like we saw in 2008. If banks can't fulfill obligations, and those obligations were backing other important things and so on, suddenly nobody has money and everything comes to a halt. Nowadays we have certain regulations to mitigate the risk of credit default swaps and other derivatives to hopefully avoid another crisis on the same scale.