I agree, and given that every UK concessionary card is an ITSO smartcard the rules of each concessionary scheme should mandate that reimbursement payments to operators are only made for cards that are scanned electronically so they lose out if drivers "wave them through" without good reason or the operator won't invest in ITSO capable ticket machines or doesn't keep them updated to read all cards. Plusbus is also moving to ITSO, and is already available on smartcard in some locations, so that should also improve the availability of usage statistics.
Given the very small number of ITSO rail tickets, ITSO plusbus in any great quantity is a very long way off.
The way ENCTS revenue is shared out is very, very complex, but is enshrined in law, so any change would require a change is law. However, any unrecorded journey does not get the operator any revenue. It can be recorded manually by the driver or electronically by the ITSO reader. The only advantage an ITSO reader has, is that it knows the issuing authority, this is of no use to the bus company, so they can't justify investment into ITSO for that alone. It is also very complex to programme into ticket machines, and therefore programming is usually done by the local authority, who get all the details of all other local authority ENCTS. However, sometimes an authority will change the chips in theirs with no time for other authorities to update the programme. Therefore the machine will not recognise the ENCTS pass, and the driver waves them through.