Software, just like so many others on HN. The trailer is an RV we take out every couple weeks during the nice weather season. It takes over 1300 pounds of payload capacity just for the trailer itself, which doesn't leave much for anything else (hitch, cargo, humans, canine). That's how I ended up trading the F150 we had for an F250. And yes, the F250 is pretty big. It's actually not a lot bigger dimensionally than an F150 (same cab, even), but it's usually taller, and it has a very stiff suspension and a live axle in the front, so it feels a lot bigger. Thus why mine rarely goes anywhere it doesn't need to go. My Model 3 is far more comfortable as a daily.
The F150's towing capacity appears to be 5,000 to 14,000 pounds (random source: https://veteransfordtampa.com/ford-f-150-towing-capacity). You could tow a 1,300 pounds trailer with a regular car, e.g. the 2023 Ioniq 5 has 2,300 pounds of towing capacity.
No, he's not towing 1,300 pounds, he's towing something that reduces carried cargo capacity by 1,300 pounds. (The impact is, IIRC, typically a bit over 10% of loaded trailer weight.)
Unless these sites use different measurement systems for towing (could be, I have no idea about these things), wouldn't a much smaller but more powerful car do?
In Europe people regularly tow RV trailers with Volvo V60 wagons...
Having looked into RV trailers in both the US and EU, I can say that the US trailers are by and large MUCH bigger than in the EU. A quick Google search showed a trailer[0] on sale in the UK, weighing in at 3289 lb. This is a typical size that I would see being towed around where I live in southern Germany.
In the US, a typical trailer[1] size could come in at ~4500 lbs. Mind you, this weight is what we call dry, not counting the weight of a filled fresh water tank, important living items (i.e. food, dishes, clothing, etc), and any other items you might want to take camping.
Although this is (slightly) on the more extreme side, "fifth-wheels"[2] are also common to see on the road. These certainly require larger vehicles to pull.
Isn't the F250 a huge vehicle and that trailer seems huge, is it a boat?