Just to put this into perspective, I work in aviation (engineering dept.), another industry that's been battered by COVID. At the end of last summer, to avoid compulsory redunctancy, we agreed to: take a 5% pay cut for the next 2 years; give up the 4% rise due the April; a layoff clause being put in our contract and to take a 10% (3 days for me) permanent cut to our annual leave allowance (to be reduced over the next 2 years). In 2022, when this agreement ends, we then go onto 'market rates', whatever that will be!
Some 20% of the workforce also took voluntary redundancy (statuary only, no enhancement)
A non-agreement to this would of resulted in a fire & rehire policy on far poorer T&C's if you were lucky enough to keep your job. We didn't really have a choice, as a strike was pretty pointless given the state of the industry.
If the railways are 'only' having a 2 year pay freeze, they are doing very well indeed.