> Only difference is that if you put it on the internet it's like building that shed in a public park
The difference here is that code published online has no assurances of being correct or adequate to the task.
Someone building a shed in a public park is, as far as I'm aware, generally not a regular occurrence and certainly you'd agree that a building on public property could be reasonably assumed to have been built to some sort of safety standards by a public body. There's a tacit agreement that, if I enter such a structure, I can reasonably assume it won't collapse on me due to poor design.
Code, on the other hand, is published online by hundreds of thousands of developers everyday. No reasonable individual can expect that any selection of that code is likely to contain anything that can be considered production-grade. Why are we taking the liability from the irresponsible corporation whose service gets pwned because they didn't review my shitty experimental crypto before using it?
Even popular and well used libraries and software shouldn't be held to this standard. You're expecting people who are building something in their free time to bear legal responsibility for the mistakes of an organization who is paying nothing to use their software. That's beyond not fair -- that would absolutely kill open source software and completely ruin the current ecosystem where a single developer and huge enterprises are on a similar level from an access-to-technology standpoint.