I'm not familiar with Volvo, so how they calculate towing capacity interested me.
I looked up some data on an XC90 on Volvo's website just to get an idea. It does show a max tow rating of 5k lbs (with the note "when properly equipped") unless you have a front wheel drive. Then it's 4k lbs. I also read that this rating only applies to towing in altitudes not to exceed 3,280 ft above sea level. For every additional 3,280 ft above that the tow rating is reduced by 10% to account for decreased engine power. But they don't do a very good job explaining what "properly equipped" means.
It doesn't appear to be cut and dry, which is no different than a Ram or any other vehicle that tows. Volvo and similar vehicles which aren't really designed with towing in mind are very vague in their tow ratings. It will likely tow it just fine, but point being that you still have to do your diligence and look at the data for your specific vehicle, and not use the blanket statement that is in the owner's manual.
The Ford Explorer is an easier one because they do use the J2807 method. Ford also sticks this caveat at the bottom of their tow chart for the Explorer:
"Maximum towing capabilities are for properly equipped vehicles with required equipment and a 150-lb. driver and passenger and vary based on cargo, vehicle configuration, accessories, option content and number of passengers. See label on door jamb for carrying capacity of a specific vehicle. For additional information, see your Ford Dealer"
Further down, they also include this:
"Under certain conditions, however, (e.g., when the trailer has a large frontal area that adds substantial air drag or when trailering in hilly or mountainous terrain) it is wise to choose a vehicle with a higher rating"
"Your specific vehicle’s tow capability could be reduced based on weight of selected trim series and option content."
You can't just say that if the manual says you can do it, that you can. These manuals are written generically with enough legalese to get them out of any potential lawsuits. You have to put in the effort to determine what is safe and practical versus what the advertisement said it could do.
I understand all that, of course, you should use your brains before you attach a trailer to your vehicle. And "properly equipped", if you go the official dealer, they will tell you that it has to have a factory installed hitch receiver, which my Volvo has, a brake controller, which I am not sure if it has, but can be easily added, and the Trailer Safe Assist is already programed in the electronic control unit as part of the Digital stability control system, and is triggered once you connect the trailer electrical wiring, the car knows that it has a trailer hooked up and behaves accordingly. That's it. Besides that, my Volvo is equipped with rear self leveling suspension, so no squat there when you start driving.
And of course, you take in consideration all other factors, how many people you have in your car, how much luggage, the altitude, all the rest, in three words, use your brains to be safe. And no one in the right mind will use the car to tow a trailer at its maximum capacity, the dynamic loads on the car, specifically on the hitch, during driving might be a lot higher than the rated numbers. That's why I think being at around 2/3, or maximum 3/4 of the maximum towing capacity would be safe.
And we started this talk here when I compared my 2007 Volvo to the 2012 ram 1500, which is also pre- J2807 standard, and everything that I said about what would a dealer say, and about being properly equipped would apply to the Ram too, and any other vehicle before 2014. So, apples to apples. At the end of all, use your brains. And at a dealer, the first thing that they will do when you ask them how much you can tow, they will open the same book or same online information about your vehicle that you have already found. They are just salesmen, they will not assume higher numbers out of nothing, as you said, it's all liability and lawsuit. Here's the book, there's the numbers, follow recommendations. 2007 Volvo xc90 - 5000lbs when properly equipped, 2012 Ram 1500 rwd - 3600 or whatever lbs towing capacity, also, when properly equipped.