Do I expect too much?

A nut, bolt and washers, sandwich materials together. We can measure torque to yield, bolt stretch, or torque plus. Long stock "torque to tone"

Screws and washers, hold one surface to another. They do not sandwich top to bottom, only surface to surface.

We use helicoils to increase the cross section of the securement.
EX: A Stainless bolt is used to secure two aluminum pieces together.
For more surface area (thread to material) a helicoil is used. The coil is harder than the hubs of hell. The bolt is hard, the washers are hard, the coil is hard. BUT the materials being joined are softer. The outside of the coil is much larger that the SS bolt..

See where this is going.. Small bolt, lots of tensile strength (so they DON'T stretch). Aviation standard.

The manufacture (in some cases because of warpage), will increase the number of securements on the face. The head of the securement is all you have to bind with.. I'd use a binding SS star washer under the head and a thread locker. Blue (Loctite) and a binding head aught to do it. Let it dry overnight. Red is metal to metal, white, is loosen with heat only.. Blue can be used with wood.. This is where the driver manufacture are coming from.

A great cheap way is interrupted threads. Different thread count (very minor) via nut and bolt. A wider binding HEAD (cap bolt or screw) is a good idea too. Wider binding area under the bolt head.

OP, I have very gentle hands, that can pull inch pounds or (LOL) 1600 foot lbs.. Yup I use to torque without torque multipliers to 1600 + with a 6 foot cheater, Spreading track..

Finger tight is finger tight PLUS 1/4. That is a torque Plus method.
Believe it or not, it works because you do recheck it many times.
With loctite, you don't recheck, you just go over the pattern several times BEFORE the binder dries..

If you keep up with the maintenance, they should stop backing out, once you get it "TIGHT".  Could take several times over a month or so. A cross pattern, then around the clock, two more times..

Back to, brass screws.. sonic difference? Better ears than mine!

My stuff don't come loose unless I want it to. Simple as that. :-)

Regards

I expected more - am I wrong?

Yeah, most of us would know what that is. Finger tight is not as tight as you can possibly tighten them. It's about when your fingers start feeling resistance and the torque needed shifts from nearly nothing to really something. That range is about 1/8th of a turn.  Anywhere in there is fine.  Get there and add 1/4 turn.

However, if you are worried, mayhaps what you should rely on is not the pressure but Loctite.

Add some to the end that attaches to the driver. You’ll get a permanent lock that won’t strip the screws. If you ever need to remove it, you can, but vibration won't cause them to loosen again.

I would only use the Loctite that is not permanent.  What if for some reason down the line you want to remove a driver?

Follow the manufacture/distributors recommendation.  Do not over-tighten.  I would not use any thread lock either.  Seriously, you’re trying to over-think a simple operation.  

Maybe think about replacing the existing screws with treadlocking ones, something like these would stand a better chance of staying put.