IMO Canon has been really, really slow to react to digital in this one regard. Av and Tv modes were invented with the addition of meters in camera, and at the time you could only change ISO by swapping out the roll of film.
That film-centric thinking is still with us, even now where you can change the ISO on the fly.
What Canon needs to get their heads around to thinking is that:
AV Mode = Aperture and ISO priority mode
TV Mode = Shutter speed and ISO priority mode
So we have a missing mode. Where is aperture and shutter speed priority mode? Canon decided to glom this on to M mode with auto ISO, except then EC doesn't work. Because it is M mode. Except with auto ISO, it isn't M mode anymore. It is aperture and shutter speed priority mode and it dang well needs EC.
For the OP - the reason your digital camera underexposes is because blown highlights are gone forever and un-recoverable. So the default for unthinking operators is to give some margin on the highlights. Canon figures if you are smart enough to ETTR, then you can manage a bit of EC......until they left EC out of aperture and shutter speed priority mode that is.