I’m afraid you’re just wrong here.
If there’s a limited train service to connect into, then the buses will likely run. But if there’s no onward connection into a train at the interchange point, then it would be farcical to run the buses. No matter how well strikes are publicised people will still turn up completely unaware that the normal service isn’t running. (My next door neighbour did exactly this yesterday, turned up at our local station en-route to a restaurant date for a train that wasn’t running because of the ASLEF strike.) At least if they find out there’s no service at their home station, they can change their plans without further inconvenience. If they don’t find out until they’re getting OFF the bus at the other end, I suspect staff would be in danger of assault.
But what is the difference between, say, GWR running services to Plymouth and no further (meaning passengers to Penzance are stranded) and running replacement buses from Oxford to Didcot even if there are no trains to connect into?
Ultimately, unless there's a normal timetable running on all routes, there is always the risk of people getting stuck on strike days. That's not an excuse for not bothering to run replacement buses that were already planned (yet still likely being liable for their costs).
As I say, it's an attitude that is utterly wrong. It treats all customers as idiots.
Whilst some may not do the amount of prior research that the industry would like them to, firstly that should not be necessary in the first place. There should be a basic level of service on all routes on strike days, and hopefully the Minimum Service Level Bill will ensure that.
More importantly, any risk of assault would be greatly reduced if the industry actually bothered to comply with its obligation to provide alternative transport or accommodation for those who had already bought a ticket before the strike or resultant timetable was announced/indicated.
But the difference with the train service is that it is rail staff and there will be announcements about strike services etc, provide advice/assistance etc, exactly what you saw. With RRS it’s a contract coach driver who is paid to drive from A to B and is very unlikely to provide any onward travel info for passengers. Sometimes you don't even enter the station in order to board the bus.
Then provide staff at either end to assist passengers. It's really not rocket science; the industry has simply developed this policy since Covid, and will now use any old spurious reason to try and justify it.