Number of US-style pickup trucks on UK roads up 92% in a decade, data shows

Emotional support vehicles.

Anything they purport to do a van can do better.

There's towing a fifth wheel trailer. Not sure if they're a thing in the UK.

searches

Sounds like it:

https://www.ccrv.co.uk/

CCRV: The Best Name in UK 5th Wheels

Whatever your fifth wheel need, we've got you covered

https://en.wikipedia.org/wiki/Caravan_(trailer)#Fifth-wheel_trailer

A fifth-wheel is a travel trailer supported by a hitch in the centre of the bed of a pickup truck instead of a hitch at the back of a vehicle. The special hitch used for fifth-wheels is a smaller version of the one used on 18-wheeler trucks and can be connected by simply driving (backing) the tow vehicle under the trailer. Fifth-wheel trailers are popular with full-time recreational vehicle enthusiasts, who often live in them for several months in one place, using their pickup truck tow vehicle for local errands. A fifth-wheel trailer tows more securely than a traditional travel trailer because the hitch weight sits directly over the pickup truck's rear axle or tires. Since part of a fifth wheel sits in the bed of the pickup, it reduces the overall length of the vehicle-and-trailer combination while allowing the same room as a comparable-length travel trailer. Additionally, the hitch's location in the pickup's bed reduces the risk of jackknifing and allows for more maneuverability when backing. Because of the greater room available on the roads in North America, these vehicles are more popular in the United States and Canada than in Europe or other parts of the world. For uneven terrain, a gooseneck hitch is an option for fifth-wheel trailers.[citation needed]

The downside is that the hitch takes up room in the pickup truck's cargo bed regardless of whether the trailer is hitched or not. The hitch can be unbolted from the bed but this takes a lot more time and effort than the unhitch operation.[citation needed]

The largest fifth-wheel trailers are full-size semi-trailers that range from 14.5 to 17.5 m (48 to 57 ft) in length and require an tractor unit as the towing vehicle due to their weight and the use of air brakes.[citation needed]

What's wrong with a van? They have barely any increased footprint over a standard car (unless it's a long wheel-base) and at least they're practical for those that need it for work. Pickups are bad vehicles to drive, bad vehicles for any form of work (outside of a few very specific things), bad for the environment, bad for pedestrians (especially children) because of the decreased visibility at the front, and bad for other road users because of how much extra space they take up.