I received my first 15.6" TS panel one year ago and it took me 6 months to get it working the way you described, lots of noise, sensitivity not so good. I was about to give-up but learned i could pass some parms to the TS hardware to minimize noise and sensitivity and by trial and error i achieved reasonable results, so i ordered a new one from the same supplier.
I got a different one, slightly larger, that was i suppose from another manufacturer and guess what, it worked like a charm, very pleasant, similar to my cheap android phone with capacitive touch (yes, the one i took the blurry video, i dropped it and i think the camera detached from the gorilla glass..).
I know now the first panel was good for shooting target, a trash.
So not all resistive TS are made equal.
This 18.5" TS panel were taken from an older poker machine, just to be sure it would work and as a proof of concept and for the prototype. This one is also good for...cof,cof, mirroring.
The only thing i know for sure is that the error, the noise and the sensitivity increase with size, perhaps the usb module has some very cleaver algorithm to minimize it.
Finding a good resistive TS is the key.