The current compensation regime wastes significant amounts of money because the government have taken it as a soft option in the face of a worsening reputation rather than doing the actual hard work of improving punctuality and reliability. Nearly everyone who is using the railway as a ticket holder would rather have a good service (that they've paid expecting to receive) than a few pounds back. It's part of why claim rates are still quite low despite their growth in recent years. Certainly the recent trend of paying out what's often just a few pence for 15 minute delays is ludicrous.
Greater Anglia are doing OK it seems:
Average annual punctuality for the whole of the Greater Anglia network is now at 94.57 per cent.
Punctuality on Greater Anglia’s intercity services between Norwich, Ipswich, Colchester and London have reached an all-time high of 94.2 per cent of trains arriving on time on average throughout the year.
Meanwhile average annual punctuality for other services on the Great Eastern Main Line between Ipswich/Colchester/Clacton/Walton/Harwich and London Liverpool Street is at 94.6 per cent, with 94.8 per cent of trains on the Southend Victoria line running on time throughout the year.
On the West Anglia line between Cambridge/Bishops Stortford/Hertford East and London Liverpool Street, 94.2 per cent of trains have been on time over the last year.
Trains on the Greater Anglia’s regional services have also achieved very high annual punctuality. The top five routes are Norwich to Great Yarmouth with 98.2 per of trains on time throughout the year; Norwich to Sheringham at 97.5 per cent, Norwich to Lowestoft, 97.4 per cent; Marks Tey to Sudbury, 97.2 per cent and Norwich to Cambridge 95.9 per cent.