Why will companies hire you, but not buy code from you?

>When I tell the recruiter ...

You are anyway talking to the "wrong" people.

A recruiter is generally an external consultant that has nothing to do with the actual company, he/she is tasked to find candidates for a role (and nothing else, and they are paid for providing these candidates only).

And they won't give you a contact to the company, let alone to the people inside the company that can overrule a taken decision "let's hire someone to do this" with an alternative.

If you manage to get to know the company they are recruiting for AND you manage to speak to its CTO (or whomever takes this kind of decisions) then you might have a chance to propose the alternative of just buying the code.

Even if you sell your IP, the fact that you developed it outside of the company (i.e. on your own laptop, using third party software with your personal account) poses some risk for them. Whether this risk is justified obviously depends on what you're developing, etc.

For their IP, companies like "clean" assets -- stuff developed by employees on company systems. This is also true from an operational standpoint (if they want to customize or integrate with other in-house systems), they'd rather be able to do that in-house.

I worked in-house for a company that would literally spend waaayyy more time/money on building tools than licensing or buying them from somewhere else just because they didn't want to deal with the risk/headache.

It's a rare and crappy company whose software needs are so discretizable that it can fire-and-forget a work assignment without confidential access to its existing infra/data, and without longer term handholding.

If your bread and butter is implementing projects for dishonest cs students, that would make a lot more sense.

They would own the IP rather than you and thus prevent a competitor from also getting access to it. they would also control where, how, and what you work on rather than you.