I am lucky to live near several locations where scrub-jays live. One of the locations is a sanctuary and all the jays there have been banded and are tracked. It is a relatively small location and they run into a lot of people on a daily basis. It is surrounded by houses which I am sure feed the jays regularly.
For this reason these jays are extremely tame and “friendly”. Just the fact that the birds have been caught and banded and then released means that they will be much more tame around humans.
If you hold an acorn out they will land on your hand. In fact it has become quite a tourist attraction for those looking for a neat experience or those looking to capture that next great Instagram photo.
In the deeper woods the un-banded scrub-jays are much more cautious. They will not swoop down and land on you. If you hold out an acorn they will come near to investigate what you are up to. They generally act more wild. They perform a herky-jerky movement to constantly check out the situation and to look for predators as well.
If you visit them enough, the wild birds will become more friendly with you and more comfortable around you. They have an uncanny ability to recognize individual humans. All corvids do. It is something which has been documented in scientific studies. But they do not necessarily trust the people you may bring out there by association only. I have brought friends out into the scrub and the jays have kept their distance. Also, if you bring a dog with you there is very little chance they will approach you. I have seen the jays alert when a dog is in the area and then they will seek a higher perch. Sometimes I will know if there is a dog elsewhere on the trail by the birds behavior well before I actually see the dog and their human.
For the wild scrub-jay every day is a game of life or death. At any moment a bobcat or a hawk could be lurking around looking for its next meal. Scrub-jays have spent thousands of years living on the ground level alongside humans so it is natural that they have studied us, know that we are mostly friendly and have movement limitations. Catching a bird that doesnt want to be caught with your bare hands is next to impossible.