People also post land because, while they may be fine with people walking, they may not be fine with people hunting and ripping up paths with ATVs and dirt bikes. (The latter group regularly rips down my neighbor's posted signs.)
You can post against specific uses "No Hunting" but not "No Trespassing"
A quote from my states website
The landowner may maintain signs that:
Prohibit hunting, fishing or trapping;
Prohibit any combination of the three; or
State all or any combination of the three are allowed
by Permission Only.
Once registered, Permission Only signs and standard Posted signs are essentially
identical in meaning and enforcement. However, if you've decided to post, consider
Permission Only signs when:
Your primary goal is to know who is using your property;
You welcome hunters, but have had issues with other users;
You've made the decision to post, but want to show you support hunting and use
hunting as a tool on your property; and
You want to continue to allow other public access without written permission, such
as hiking and cross country skiing.
Yes. Around where I live (New England), it's fairly common to post land without a blanket "No Trespassing" with the intent to prohibit motorized vehicles, hunting, and trapping but not people simply walking on your property.
It still happens though that as rural towns become more like exurbs though that new landowners post their properties to prohibit "traditional" uses that long-time residents had been doing all their lives.
