Contact start / strike arc welding is simply just older technology and has nothing to do with the quality or ability to control a weld.
A lot of chassis builders are dealing with tubing joints that require a lot of precision to start the arc, so I can see how this could aid them, but there are ways around it.
Typically on complex tubing joints, like in cage builds, you need a lot of stickout on your tungsten. This inherently requires a diffuser and larger gas lense, to adequately protect oxygen from the work.
The reason you go with the pedal is actually because of the ability to control the weld on the fly. When you are dealing with odd shapes, it is very difficult to use a hand trigger and produce anything, except for assembly line results on continuous, small or short bead passes. Like if you are doing a hundred 1" stitches on 3/16" stock.
Cars need a lot of control, because you are inherently dealing with a lot of different thicknesses and positions of metal, sometimes even several thicknesses and angles at once.
This is actually the reason that I elected not to get a water cooled torch. I use a CK 17 whip that keeps the torch light in my hand and I run the whip off of the foot pedal that I made, so I've got less line tripping me up. I have whip in a velcro loop attached to my belt loop on my pants, with a single loop, so I can adjust whip length from my hip to my hand at any time, but only carry the weight of the line that goes from my hip to my hand, to help control and keep from fatiguing.
I run a 185 amp machine that has 110 and 220 voltage input capabilities. I've tripped the shitty breaker in my old garage on it, but that doesn't say much, because the whole thing was on a 20 amp. I have yet to trip duty cycle.
Typically, you won't hit it on a project when working on cars, because nothing requires a weld to be done, that long, on a car. Heavy welds are usually simple joints, like on frames, motor mounts, cages, spring purches, etc. It is not common to push a bead that is several feet long on anything that is beyond sheet metal, and the last thing you want to do is burn a bead that long, without stopping, on sheet metal.
I have yet to find a use in the home garage for a water cooled torch, unless you are doing nothing, but welding all day, you simply don't need it. It's only going to cut down on your accuracy, control and increase the weight and difficulty to weld. If you've got one, by all means, use what you've got, but don't worry about it if you don't have it, working on a car or hobby level use of any kind.
If you are doing heavy work, be sure to get a good size tungsten and go with something that will hold up, like a 2% thoriated, versus a 1.5 or 2%lanthanated. I've used them all and I think the thoriated can be used on anything. I like 3/32" for most work. I'd suggest to go a little bigger on frame work.
