I presume that if the software is non-trivial, Google's chequebook can convince most open-source maintainers.
That is likely true. But I also know FOSS developers who outright rejected very large sums of money being offered for their work. From a combination of principles, values, not needing the money, or not willing to take responsibilities that come from such sale and/or restrictions of freedom that would mean. The "they just buy it" is the cynical assumption that everything always revolves around money. It often does, but not 100% of the time.
But now we are not talking about the sale of their work but simply licensing. J have not heard anyone rejecting large sums for licensing g code.