This is my biggest frustration around the discourse around public sector pay (which now includes rail staff) for the last few years/since 2010 - you can only really take one long term position:
- Pay should increase each year on average (either measured by inflation - CPI or RPI or wider earnings growth)
- Public sector pay should progressively get worse over time, either because they don't deserve the increases, they aren't making productivity improvements, or it's an unfair burden on the taxpayer.
If you are arguing for option two, then don't be surprised when you get strikes. Inflation pay increases are the norm in the private sector[1] and this included the privatised TOCs. Trying to renege on that is unfair on those it effects.
If you are arguing for option one, you can build up goodwill to leverage this for a short period - e.g the junior doctors who accepted significant pay stagnation until it became clear the government had no intention of restoring the pay in the long term and initiated their significant industrial dispute.
I think that in an idealistic world, there should be an automatic link to earnings growth, perhaps with some flexibility around averaging over a three year period for example - and I would also be comfortable with then linking this to a minimum service obligation, written into any contracts issued to new members of staff which would provide some resilience in the long term - I accept that proposal alone would cause significant discontent with the unions and isn't likely to be easy to achieve.
This is slightly more off topic but I'd actually go further and suggest that the broader pensions triple lock should just be linked to earnings growth, to give pensioners a wider stake in the opportunity available to people of working age. And historically (until 2008) earnings growth has outpaced inflation.
[1] not everyone gets a pay increase every year, those who do are fortunate - but in aggregate, private earnings growth has been higher than public sector earnings growth for much of the last 14 years. This has led to other problems, in particular the ability of the public sector to recruit high quality employees - for example, my current role in the private sector pays 4x an equivalent public sector role advertised in the cabinet office last year - and the over-promotion of people to retain them when simple private sector pay negotiation would have done the same job without the accompanying reduction in overall competence.