Nobody should be debugging code by hand either but when all the tools fail, its time to get your hands dirty.
I agree with the below poster, this reeks, no one is doing o-scope level debugging on a production vehicle. It's what someone would say that has no idea how cars are designed, built, and serviced in reality.
https://www.snapon.com/EN/US/Diagnostics/Products/TRITON-D10
It’s slow but it’s an oscilloscope. It graphs electrical measurements over time. They sold CRT scopes on carts for years and years.
Maybe you should move the goalposts and demand FFT or higher bandwidth.