Presumably there’s a karmic payoff for this, or someone at X company knows someone at Y who can tell them whether or not you’re actually in the pipeline or have received an offer. Perhaps there’s an element of bluffing or calling bluffs in all of this.

I like karma, but wouldn't checking have the appearance of illegal collusion between the companies? For example, would it look like they were price-fixing?

"Oh, your honor, I was only checking whether they had an offer. We totally weren't discussing how we'd not raise our offers, with the goal of suppressing wages."

iirc there’s already an app for that in some sense, and a good amount of plausible deniability and backroom politics that can make up for any potential lawsuit. Similar issue to “proving” any kind of discrimination: a smooth corporate operator can CYA well enough to create a fake paper trail to justify any sort of decision making.

I mean, that sounds like a level of due dilegence that a lot of companies are unlikely to follow. I suspect that most don't even check the references that you give them.

False. Whatever you got told in primary school was a lie.

Would you be compelled to tell them the offer was from company Y? Or are you saying this is all predicated on Y being a famous company?

It is a labor law violation to disclose such info.

there is also the risk of getting black listed for lying.

I’d file that under the karmic payout thing. I personally hire and fire people but don’t have The Blacklist handy, and I’m not really sure that it exists outside of Roko’s basilisk-esque sense, in which it could be really bad if it really did.