Putting code in escrow is usually done as part of the contract between the business and the customer, and the code is in escrow for that customer not for everyone.
Sure-- the point is the escrow infrastructure already exists. And it's been used the exact way I describe.
See e.g. https://en.wikipedia.org/wiki/Source_code_escrow#Software_op...
The article talks about Medicare subsidising 80% of the purchase price for many customers. That'd be a fairly effective place to negotiate such an escrow contract.