Canon EF-S vs. EF Lens shaprness when shooting with APS-C

Since Canon EF-S (S for Small image circle) are the main lenses used with APS-C format cameras, I was wondering what is their quality. There are no L lenses in the EF-S format and I wanted to put them against a similar, kit-grade lens.. I did very simple and un-scientific test and compared 3 lenses - Canon EF-S 18-55mm 3.5-5.6 IS STM, Canon EF-S 55-250mm 4-5.6 IS STM and Canon EF (Full Frame) 28-105 3.5-4.5 USM. These are very inexpensive lenses - both EF-S lenses are often sold as part of the Canon DSLR kits and the Canon EF 28-105mm which was an average (not too shabby but nothing spectacular) lens from the 35mm film days - the one I used was the "better" mark II version (f/1:3.5-4.5, 7 blade, made in Japan). It was a good. well built all-around lens and and a step up from"kit grade" econo zoom lenses at the time (as the EF 35-80mm - a really cheap lens).
All shots were taken with Canon EOS 70D set on manual mode, ISO 500, fully open aperture. The idea was to compare the details in the image thus the lens sharpness. All images are a 100% crop - 1200 x 1000 px  from the original pictures. I chose a subject with a lot of dust particles and imperfections rendering small details.

 EF-S 18-55mm @ 55 mm

 EF 28-105mm @55 mm

EF-S 55-250mm @55mm

Now, this comparison is not quite fair as both EF-S lenes were tested at their very limits where performance is not usually very hot. Still the 28-105mm is the worst of them all even almost in the middle of the zoom range.

Canon EF-S 18-55mm @ ~26mm

Canon EF 28-105mm @28mm

By far - the worst case!

Canon EF 28-105 in "Macro" mode @105mm as close as it will focus.

Canon EF-S 55-250mm did not have such close focus range so I brought the zoom to 166mm to get similar framing, Again it did outperform the EF 28-105mm

So as it turns out - the lenses, bundled nowadays with the Canon DSLR kits are of a much better quality then what you'll get in yester years and will outperform what was considered "an average" lens 15 years ago.