I think it should be the other way around.

Google is a very large company. They have capital on hand and an established, well-worn process for onboarding. It costs them comparatively little to hire.

For a small company, an engineering hire is a big investment. They don't do it as often, so it costs them more in terms of both direct costs and indirect costs - like the time it takes their existing team to go through the process and bring the new hire up to speed.