I've had "replace plastic with steel lines" on my to-do list since 2014, but haven't had the heart to cut off their water supply. That, and laziness.
They've been around my home far longer than I have, so I guess I'm the invasive species. I'm grateful they've traded access to water for snacking on my dog.
And it's my (illusory) hope that they'll eat the occasional gopher while they're in my yard. The gophers compete with me for food. The coyotes don't. Yet.
It's possible, as another poster mentioned, that they can hear water flowing through the lines. The surroundings are utterly quiet, and I run the irrigation at night. I can hear turbulence noise in the lines before the water emerges from the local applicators.
On the other hand, coyotes are canids. Their sensory skills are optimized for olfaction. Maybe they can smell the minuscule amount of water vapor that leaks through the push-to-connect couplings. Plus they seem to be pretty smart. It might take only one coyote Einstein to discover "plastic lines here = water" and pass it on to the pack.
They'd gladly "snack on your dog" or your child, given the opportunity.
If you’re talking about a casual garden, I’ve got nothing for you other than (maybe) metal lines.