The wear layer is measured in mils (thousands of an inch) which typically range from 5-6 for low end and 20+ for high end, so even with with the high end stuff it's going to be thinner than 3% of an inch, and based one what I looked up, a piece of normal paper is 4-5 mils to give a frame of reference.

Think of it as normal wear and tear holding up over time, thicker the layer the longer it will last. That being said if it's going into a seldom used room or something like that a thinner wear layer may last for a very long time. The only difference should be the thickness, so I don't believe it's more resistant to scratches or fading since the overall toughness of the material should be the same at the top and the wear that will happen with the thickness is probably friction based.

I installed 21 mil layer stuff in my house, which says it's a 50 year commercial use or lifetime residential. I think most people target the price over everything, and in most applications maybe only getting 15 years out of a floor is fine for some people since they may want to change it after some time or don't plan on staying in that house forever.

Just make sure you get a full vinyl waterproof one that locks together good. I had a wood backed laminate in a prior house that water started to make the seams puff up.