"Exactly how many car lengths of visibility advantage is gained by driving a taller variant of a typical family hatchback?"

You can better see over other vehicles. That's good.

Perhaps we should all buy monster trucks then? The downsides of SUVs are:

They don't handle as well as comparable hatchbacks, estates and saloons because their centre of gravity is higher. Many will need the assistance of extra systems or where they kick in far more often to offset that to a degree. They are also more sensitive to wind buffeting as they are more high sided.

They are less aerodynamic and heavier, and thus have lower mpgs and are not as quick for the same engine size and useful interior space.

They cost more to buy (often 10-15% more than the non-SUV equivalent) because of the extra size and safety / handling systems, and will likely cost more to insure.

Unfortunately, most SUVs sold have no offroad ability, so the extra ground clearance they may have isn't really used, especially when most will also come equipped with low profile tyres.

Some may look nice, and some (like the Mazda CX-30) can be useful where the car they are derived off (Mazda3) has flaws in terms of practicality (hatch version has a 360L boot vs 430L in the CX-30, Fastback has a bigger 450L boot but a small opening compared to the hatch on the CX-30).

Sure, the extra height can be useful to see ahead, but as others have said, if everyone had one, that would (and is) disappear. I actually preferred the seating position of the non SUV car to the more upright one of the SUV (I tested a gen-3 Mazda3 vs a CX-3) - the better handling of the lower-slung car made the seated experience more relaxing as you don't get 'thrown around' as much when cornering at reasonable speeds. Fine otherwise.

More anti-SUV thinking.

While it has better visibility allowing improved awareness of what may be going on ahead, another reason I and several friends like SUVs or Crossovers is they are fare easier to get in and out.

No pushing your body weight from a low position putting more pressure in the knee joints.Leg out, on the ground off you go.

Contrary to Sammy1's view, my wife is 5ft 4in, and has no problem getting in my SUV, neither does a 6ft5in male colleague - who also has an SUV type car.

It's what people prefer, and their popularity cant be denied.

But back when I drove buses, I used to ponder what it would be like to drive a double decker from upstairs..............

Now that definitely would give an advantage in terms of view!

When I was a kid I always wanted to be at upstairs and at the front. I used to hold the dash mounted mirror and pretend to drive. Sometimes I'd look down it to see the disgruntled drivers eyes looking up at me :-)

I liked the sound of the engines and tranmission whine too.

But back when I drove buses, I used to ponder what it would be like to drive a double decker from upstairs.............. Now that definitely would give an advantage in terms of view!

Like Mr.Bean in/on a Mini, you mean ?

I do sometimes wonder about the wisdom of driving SUVs for visibility reasons. Once everyone has one, will we need to get some kind of giraffe car to see over the top of those?

I get the accessibility thing, but I mostly bought an SUV because of the lack of choice amongst 'proper' cars. Most manufacturers seem to reluctantly offer one mid size hatch/estate that they don't really market and then a whole load variations of 'car on stilts '. VW are the worst; they have something like five different indistinguishable boxes on sale.

Higher SUVs get less dirty around the base areas and other body work.Quicker to keep clean/wash

Do they ? Why ?

With the height advantage it also helps seeing over hedgerows. Think for example driving down a twisty country lane, you can often see what is around the bend before regular cars can,

At our time of life when the offspring went to uni, we traded our Cavalier estate for an ex-demo Mk.1 Prairie (the brick-shaped one, as the salesman said). It lumbered along with its 1.8-litre engine, getting 40mpg or thereabouts, and had a useful load volume and a double-bed capability. But the high seating position was memorable for the time (about 1989).

The rule of thumb is that when you stop ( traffic lights ) you should be able to see the road in front of you. But you cant blame the vehicle for bad driving as it is people who do the driving not he vehicle itself.

You can if the design of the vehicle limits forward vision. When I replaced my Pug 306 with a 207SW one of my earliest impressions was the difficulty of seeing anything ahead when crossing a hump such as a canal bridge or a Lake District back lane - because the screen was more raked, with less angle between it and the bonnet.