They are more secure than a regular jackstand since they are bolted to the car. As long a person actually tightens the lug nuts the jackstand can't come off and it can't flip in or out. It could flip around if the car got rear ended by another car, but the same force would knock any car off of jacks.

I've used this design for a long time on my own cars, just never turned it into a product. Here is a set I built 20 years ago for my Coronet.

This picture also shows why they are nice to use. The entire area under the car is open so you can slide under it to work. By having the suspension compressed everything is at ride height and the frame is taking the load as it would with tires on the car.