Because it's a lot easier for Disney to churn out mickey mouse cartoons than it is for General Electric to come up with an entirely new rotating joint for the helicopter mounted motorized minigun

Although copyright and patents (and trademarks) are lumped together as "intellectual property", there's almost nothing which is broadly applicable to them all, and they might as well be considered separately. The only things I can think of -- and I'm not a lawyer of any kind -- are that: 1) IP protection is mentioned vaguely in the US Constitution, and 2) they all behave as property, in that they can be traded/reassigned. That's it.

With that out of the way, it's important to keep in mind that patent rights are probably the strongest in the family of IP, since there's no equivalent "fair use" (US) or "fair dealing" (UK) allowance that copyright has. A patent is almost like owning an idea, whereas copyright is akin to owning a certain rendition plus a derivative right.

Disney has leaned on copyright to carve for themselves an exclusive market of Disney characters, while also occasionally renewing their older characters (aka derivatives), so that's why they lobby for longer copyright terms.

Whereas there isn't really a singular behemoth company whose bread-and-butter business is to churn out patents. Inventing stuff is hard, and so the lack of such a major player means a lack of lobbying to extend patent terms.

To be clear, there are companies who rely almost entirely on patent law for their existence, just like Disney relies on copyright law. But type foundries (companies that make fonts) are just plainly different than Disney. Typefaces (aka fonts) as a design can be granted patents, and then the font files can be granted copyright. But this is a special case, I think.

The point is: no one's really clamoring for longer parents, and most people would regard a longer exclusive term on "ideas" to be very problematic. Esp if it meant pharmaceutical companies could engage in even more price-gouging, for example.