Some coyotes are terribly high strung - shy. They won't approach situations that stress them out. I've observed their tracks during trapping seasons as they approach winter-killed moose or scent-based trap sets. Sometimes they won't even come in to feed on a natural moose kill. They'll circle around from 10-30 yards and simply leave. I've seen their tracks depart in a run from a scented trap set in the dead middle of winter. I know their behavior depends on how hungry and starvation stressed they are also. If they're really hungry, they'll take chances they wouldn't otherwise take. I've caught two in foothold traps that were set for lynx. Enclosed cubby sets that coyote will normally not approach. They don't normally approach enclosed areas. Both of these two coyotes had porcupine quills in the mouths and were willing to take some additional risk due to their hunger stress.
Some are just naturally born more shy than others. Some are trained to be shy due to having learned from prior experiences. Even lynx, which are normally pretty mellow, low-strung, and easy to lure into a scented cubby trap set can learn to avoid these risky situations and become very elusive and difficult to catch. I followed a set of very large lynx tracks one winter that approached three of my cubby sets - one after another. Circled around all three from a distance of about 6-8 feet, and simply continued on his way. Left me scratching my head. I took this as a challenge, but I never was able to catch that tom in a trap. He was obviously trap-smart. But as it turned out, he wasn't truck-smart.
Later that season I bumped into him adjacent to the two-track trail at the end of the day after checking my trapline, and harvested him with a .22 pistol from a distance of about 15 feet. Big mature tom. Smart in one way. Not so smart in another.