I'd say it is because of the time factor. It is one thing to have a lot of money, it is another thing to have robust systems that have been developed and tested for years. Money can "buy development time" only up to a certain factor.

I guess the sandboxing problem, that is easily giving access to enough resources while restraining the critical parts is still open for most of the cases, given all the startups and bit tech companies (docker, etc...) working on their solutions.