Resin

Yards don't want to say they use the cheapest poly resin they can when building. Just lay more cloth to soak up the extra risen to impress the customers.
More cloth just covers the brittleness of cheap resins.

The yards that TRY to advertise Vinyl, use just enough in the bottom sides to help reduce blister warranty calls.

Epoxy is just to heavy and expensive to build with.

I learned the hard way in a previous life, Epoxy only for repairs and small projects.
Epoxy sticks to near everything.
It's a poor gabble for resins to stick to epoxy.

On our larger models, Delta 48-54-60-88, we are using vacuum infused sandwich with Divinycell, carbon fiber and vinyl ester, with a vinyl ester gelcoat.

Most builders use Isphotalic gelcoat, with a coat of Vinilester resin (some two) and then the normal polyester resin below that.
Some builders also like the powder bound mat, which reduces blisters popping up. British builders used to do it this way just after the first layer.
With resin infusion I do not know if they still build this way, as lay up is now very much hidden.
With most now into vacuum infusion there is two main manufacturer's Divinycell which is the most widely used (also because they are cheaper) and CoreCell.
Corecell system is known to be much better especially for avoiding resin starved areas (leading to delamination) due to the engineering design of its core.
Altough Divinycell second generation Cores have closed this gap a bit.

I learned my boatbuilding trade at AquaStar, making offshore Pilot boats and fastfishers; we did 50% yachts too. Tough inch thick hulls that could take a knock or two.

The first layer was always Isothropic to counter extreme cold temperatures and cracking. Hand lamination of this kind isn't used very often today as it's very heavy and costly, that's why old 70's boats have lasted so long, we just didn't know when to stop.

I think the thickness is still more or less the same today, the difference might be that most of the new builds are cored.
It is an endless discussions if PVC core is better to older Balsa core for strength.
For water absorption resistance PvC wins hands down, although balsa core is near impossible to be resin starved.
Then it gets to what you want from strength. PVC cored boats are more stiff, which a salesman from a Core-Product will tell you is stronger.
But a boat, hence why wood is still the most sound material for boat building (not to maintain today for many reasons), and feels like a butter in rough seas needs tensile strength.

So what I am saying is that with cored boats we have the rigidity of an alloy boat but build in sandwich layers of glass, resin, and core.
Which probably is good until it comes to the breakpoint which is less to that of a traditional solid glass hull.