They have their uses.
In my rather tight parking garage we use a convex mirror, a laser parking system and a hanging 'tennis' ball. The ball is actually soft rubber, better than a tennis ball, less likely to attract idiots hitting it. A real problem with hanging markers. Almost anybody who comes into the garage wants to bat at it...
Adults more than kids.
Anyway, pros and cons of each system;
On my F150 the laser isn't too useful. There is nothing on the hood, or dash, to help you navigate the red dot. So parking with it is about useless. You would need to have a dot, line, something, on the hood to use as a reference point. If your car slopes away sharply or has no visible configuration on the hood the laser is not going to help.
The Tracker has a light sensor on the dash that is completely visible so you 'aim' the laser dot along the hood till it hits the sensor, then shut it down.
The Touring Coupe has the same problem as the F150.
Tennis ball works perfectly on the F150 as you bump the windshield near the mirror and that means you can drop the door.
Tennis ball doesn't work very well with the Tracker. There isn't enough parallax with the very short vehicle and very steep windshield. You 'hit the ball' rather than sloping up to it. Thus the ball can bounce away from the window, and then you must wait till it settles.
So laser for Tracker, ball for F150 and the mirror helps with the coupe.
Convex mirror works great with the coupe because you can tell the passenger mirror is going to clear. You can't actually SEE the mirror and the spring with the naked eye, so the mirror in the corner of the ceiling lets you tell when you have the one to three inches clearance you need.
On parking, lots of people have very tight garages, and multiple cars. Each car MUST fit in an area about three inches wider than the vehicle. The Tracker must come in with less than one inch distance between the mirror and the garage door springs. Hitting that is a bear without helper items. Also, I need to park each vehicle within one or two inches, MAX of the garage door.
My wife has no depth perception so it is harder for her (never did have it, bad vision in her left eye) but it is still hard to park to within an inch without help.
Also makes it harder if you own/drive LOTS of cars. Only have four right now, well six if you count things to big to park in the garages, but I have owned hundreds of cars/trucks over the years.
A guy who only drives one car and parks in a roomy (defined as more than three INCHES of slop doesn't cause a ding) wouldn't need any of these tricks.