Hello Harry, this is a forum for the European V40 hatchback, so I doubt many members will have practical experience of the XC60. In addition, I doubt many members will be familiar or experience with US salvage titles and procedures. I am certainly not.
I do have experience of the UK market through my work though. It may differ markedly from the US however. Here, it is possible that not all damaged cars, even seriously damaged ones, will have salvage categories. There are various ways that they can slip through the net. But for cars that have been categorized, depending on the extent of damage, they may not be allowed back on the road, or may have to undergo an inspection before being registered. The inspection is mainly concerned with the identity of the vehicle though, not its mechanical condition, and is not infallible. I have examined several cars that had been purchased by new owners both privately and through motor dealers, where the vehicle was either seriously unsafe, despite outward appearances, or it was in fact a completely different vehicle to that which it appeared to be, in some cases a rung stolen car, or more often, a car repaired with donor parts from one of more stolen vehicles.
It is not unknown for instance, for individuals to purchase the salvage of a damaged car from a salvage business, then steal or have already stolen a similar car, transfer the identity of the salvage to the stolen car, and sell it to an unsuspecting customer, who may eventually lose it and his or her money when the deception comes to light. The deception may be discovered when the car goes to a dealer for servicing or other repairs, and they notice the discrepancy, either visually or from information contained in the electronic systems on the car when it is connected to diagnostics. Invariably, the "new owner" then loses the car, and the money they had paid for it, because the seller is long gone and untraceable. Alternatively, they may repair the car with parts taken from other stolen cars and body repairs could be completed in such a way that, although everything looks good, they would be highly unsafe should the car be involved in a future collision.
Of course, that doesn't mean that there are not genuine salvage repaired vehicles on the market which have been repaired to a high standard, but the costs involved for anything but the most minor damage are often so prohibitive that it is impossible to repair many vehicles properly and make a profit.
It really is a case of caveat emptor, but as I say you are in a different market that I know nothing about (although from the professional circulations that I used to have access to, and conferences etc. that I attended before I retired, it seems to me that the US is not that dissimilar). My advice though would be to always get a professional and thorough inspection from a reputable business with guarantees. Plus, if a deal appears too good to be true, it usually is, for a reason!
You may get more responses on the Swedespeed forums, which are predominantly US/Canadian based.