Being tamper proof is a thing that you address in a systemic way, with information, analysis, materials and procedures.
So a paper ballot is not tamper proof but a box that is viewed by many that is opened in the presence of many and counted, and re-counted by many can yield a result that all will likely agree on to a degree that the democratic process can be executed.
You could try to exchange the box, but there would be many witnesses, you could try to put extra ballots in it, but it would be detected and so on. The witnesses make all the difference, they turn a tamper prone piece of paper in to a tamper proof election device.
A computer in stead of that box with paper ballots is open to any number of ways of tampering that would go undetected, both locally and remotely as well as from the outside before the election has even been started.
I don’t disagree with you in general, I just think that the whole process of the paper ballot is not tamper proof. It is much more tamper proof than voting machines, sure, but not wholly immune.
I think the statement ‘The paper ballot process is practically tamper proof’ is essentially correct and as such don’t think that the statement of the Chief Election Commissioner with regard to voting machines in itself is incriminating. All I want to say is that saying something is ‘practically tamper proof’ is a meaningful statement.
And that is definitely something that can be done I think.