Maybe you’re not considering about the whole system here. The TA exists in a Fork/endcap/Hub sandwhich, with the wheel bearings riding on the TA, the end caps help with lateral loading. In a QR, you’ve got the QR holding the whole thing together laterally, but the endcaps and an interior axle supporting it vertically. Inside that QR hub, is effectively a Thru Axle pipe, most of those are about 1-2mm in wall thickness.
Currently, light TAs aren’t all that light! I bought one just to clean up the front of my bike. A Shimano DA 9000 front axle is 34gr with (1) end caps ( 16gr end caps on the other side) - so 18gr axle. DT Swiss lists their (ebike) 12mm TA unit as 29gr. My unit is ~20gr.
They’re all made out of basically the same material. The weight savings here is from saving 9gr of material out of the center of the bolt, which is only there to reduce bending loads, which there are very little there for a whole host of reasons.
You’re basically comparing:
QR: 9mm front end cap + for a 5mm skewer. That end cap is threaded onto a (on a Shimano QR front hub) 9mm with ~1-2mm wall thickness +
TA: 12mm hollow shaft with ~3mm wall thickness (recalling my 20gr lightweight TA) ~5mm bore (based on the 6mm allen key needed) in the loaded bearing area and 1.5mm thick in the reduced center . The fork is the exact same width.
The TA drop out also have cups built in, to vertically support the end caps, should things get real. If things go wrong, that 5mm QR is going to get leveraged apart much faster than my 12mm TA because of the maneuvering room in the dropouts there. You can test this yourself at home by putting putting a QR almost all the way in and buy putting a TA almost all the way in and putting a little vertical load on the bike. You’re going to have an extra second to deal with a sheared TA.
As for things, unscrewing… as mentioned the TA dropouts are cupped and will support the hub end caps for a sec. I think both 12mm TA and QR end caps are ~20 in outer diameter. These work to manage bending forces on the axle and to slow down the face plant when the axle system gives way. If it loosens, that axle will get pinched if it moves off axis pretty quickly up due to end cap tolerances and the axle isn’t incentivized to move laterally because of the vertical load being applied. It will be a very very slow accident.
Weight reference
SJS Cycles Bicycle Parts and Accessories Store .
https://r2-bike.com/DT-SWISS-Thru-Axle-FW-RWS-Plug-In-Road-with-Lever-12x100-mm-E-Thru
J&L Thru Axle 100/142* 12mm-20g&26g-for Trek Madone/Emonda/Domane-Front&Rear | eBay