So since clearly my training having worked in the business is in the minority opinion, let's hear exactly why from those who differ.
Here's an example case to be argued:
My mother drives a 2010 Honda CR-V. Door placard recommends 30psi.
OEM Tires: Bridgestone Duelers - P225/65R17 102T
Newest installed set: Pirelli Scorpion All Terrain Plus - P225/65R17 102H
OEM set was okay at 30psi. These Pirellis are underinflated at 30psi and show a clear flat indention on the ground instead of being appropriately round. Yes, they have different speed ratings, but we're talking about pressure and it's therefore irrelevant. Both have the same load index at 102. So if the door placard is correct, why the noticeably visually low tires?
First, the steel belts in a tire can be manipulated to affect the wear pattern. There is a wedge of rubber under the edge of the steel belts and you can make the belt concave or convex depending on how large those wedges are. Needless to say that tire designers try to get a good wear pattern at the loads and inflation pressures specified by the vehicle manufacturers.
HOWEVER, sometimes there is a different goal and the result is a tire that doesn't wear well. For example, if the goal is better rolling resistance, the tire can be made such that the amount of rubber on the edges of the tread is reduced, and the wear pattern resembles an underinflated tire. It's also possible for a mistake to be made in manufacturing that results in a less than optimal wear pattern. Don't ask how I know.
And in this case, the H speed rated tire will likely have a cap ply and that affects the wear pattern, so the belts have to be adjusted to compensate - and sometimes, they aren't.
Plus, there is a way to get a good wear pattern for a wide range of loads and inflation pressures. (I don't know what it is, but I have seen the results.) That's why "The Chalk Test" doesn't work.
And to complete the picture: Inflation pressure isn't the largest effect when it comes to even wear. Steer tires tend to wear in the shoulders and drive tires tend to wear in the center - and this effect is larger than inflation pressure. Even a FWD car where both those functions are on the same axle, if one drives a lot in the city, where there are a lot of turns, the shoulder wear effect will come out.
The primary design goal for a tire is the load table. This is a MUST as it is part of a government regulation. The wear pattern comes after that and isn't covered by a regulation - and sometimes things don't go the way they should.
The pressure listed on the vehicle placard is also derived from the load tables. So there's a direct connection between the placard and the tire's durability. The wear pattern isn't so well connected and you can get odd wear patterns, even at the proper inflation pressure.
Side note: I know that there's lots of illustrations showing that underinflation generates a certain wear pattern, but it is a gross generalization. It's done to encourage people to check their tire pressures and needs to be understood in that context. Things are NOT as black and white as that is portrayed.