Yes you can indeed make all the listed errors with a GPS but it's even easier to do them with the old methods. This is the great fallacy underpinning the anti GPS position; they chuck out the baby with the bathwater.
Let's say you have a carefully prepared plan, wind corrected and all that, through CAS. You ask for clearance 10 miles out or whatever, get refused and now you have to dogleg around it, using compass, stopwatch, together with trying to identify some villages down below. All the way round you will be in need of fresh underpants because you know what that one little mistake will cost you.....
I am talking about doing this in unfamiliar territory, not in one's back yard which is where most anti-GPS pilots stick to (understandably).
There is no way round this. I am sure INS has severely degraded the ability of your British Airways ATP to use a sextant.
As for direct coordinate entry, that is almost never done in GA, if the pilot knows anything about flight planning. In 5 years I have had to do it twice; once to enter an airfield in Spain (which got put into the Jepp data the following year), and the other to enter some gliding site in Kent which a passenger wanted to take pictures of. If airline ops need nav to ever varying waypoints (to get the best winds) they have to pay the price for that, and check their numbers twice
There is nothing particularly "airline pilot" about checking coordinates; single pilot IFR pilots are supposed to do it for every waypoint, as are airline pilots; that's why the lat/long is printed next to every waypoint on the IFR charts.