This is quite interesting. Mind you, around here ALL animals have to be tagged with a RFID (CCIA) tag to be sold. So, I guess all Canadian cattle would be OK in your eyes.
Tagged or not tagged, I can't see how that tells you anything about
1. how much contact an animal had with humans. There are probably a lot of small, small herds who don't tag, because they don't need to. They KNOW each and every animal in the herd. Then, there are large herds who are all tagged. The calves are tagged at birth or branding, and that is the last time they were handled by humans, and possibly the only time they ever saw someone on foot until they were weaned.
2. how they were handled or gathered. Can't figure this one out at all. Most of us, regardless of how big we are or how we get the cattle into a corral, don't want to stress the animals much. Running them around is losing us weight, which in turn loses us money. Cattle that are used to being handled, be it on horse, by a 4-wheeler or on foot aren't generally nervous when handled in that way. Maybe you should go out and visit a few ranchers/farmers that handle cattle with horses or 4-wheelers.
3. the possibility of injury. Is always there, no matter how wild or quiet the cattle. If you can't pick out an injured animal in a larger group, maybe you need to have someone else watching too.... Most auctions won't leave an injured animal in with a group, same as a stag, or horns or whatever. Sneaking stuff in like that tends to give a bad name. Obviously stuff happens, but on the whole that isn't a good business practice.
4. Facilities to work cattle. Now how this has anything to do with whether a calf is tagged or not, I do not know. It definitely doesn't take facilities to tag a calf. Do it when they are less than a couple days old, you don't need a chute, you don't even need a corral or catch pen. Heck, you don't need a great facility to brand or even vaccinate calves in. I've seen a lot of brandings where the entire herd is run into a big catch pen (or 2). Most of the cows are sorted off, the calves are roped(by the hind legs) and dragged to the branding fire, where 2 people wrestle them to the ground and sit on them while they are branded, vaccinated and many times tagged. There may not even be a chute there. As for treating or not treating, again, it doesn't necessarily take a great facility to treat a cow, and even less of one to treat a calf. They can be roped, it is done on a lot of large ranches, where the facility may be miles away from a sick animal. And really all you need to treat is a catch pen with a chute attached to run the animal down. You don't even need a headgate.
5.Knowing whether the animal has been wormed, vaccinated or banded/castrated. Well, I think I covered that in #4. As for the banding/castrating, well, if you can't tell about that one................
6.Weaning on wheels. A lot of us do it, it has more to do with the fact of how well we do/don't get paid for preconditioning cattle. I've seen preconditioned cattle sell for a LOT less than fresh weaned calves at the same sale. Why would I spend my time, money and feed on preconditioning calves, and then make no more money than the guy that sent freshly weaned cattle to the sale???
So, I can't see how an untagged calf can mean anything more or less than a tagged calf, other than it doesn't have a tag. A tag is pretty easy to put into a baby calf, unless mama is real nasty. And in that case there are ways to deal with that that don't require a fancy facility. A truck box and a rope usually work well for these situations. Or, they can be tagged when they are vaccinated/branded. This may be the only time that calf EVER sees a human on foot up until weaning time. Genetics and the WAY the animal is handled have more to do with disposition than how OFTEN the animal is handled (or around people) Some animals just never settle. Tags can fall out, and as others have mentioned, are often removed before a sale.
We tag all our calves as they are born. The reason we tag has to do with in herd management. I want to know what my cows are doing, and it is easier to know when they are all tagged, we used to remove the tags before we sold the calves, now we don't. I'm still cheap enough to do it, but it always starts an arguement so I gave up.
I know people who tag at branding, and who don't tag at all, they have good facilities, and all their cattle are vaccinated, branded and castrated. Then again I know a few who don't tag, brand, vaccinate, deworm, castrate or dehorn. It is pretty hard to tell which is which (except for the obvious horns and nuts). I know people who are around their cattle lots and they are still wild, both tagged ones AND non tagged herds. And I know people who hardly handle their cattle, and the cattle are still quiet. Tags don't tell you anything other than that the owner wanted to ID his cattle for some reason.......