> So, net effect will be: poor people who do not use roaming (e.g. because they cannot afford vacations abroad) will pay for the convenience of middle and higher class people who travel a lot.

You'd have to be fairly destitute to not be able to afford to travel within Europe[1]. For example, even people on social welfare in the UK and Ireland can afford cheap sun holidays to Spain or wherever.

[1] https://www.ryanair.com/gb/en/cheap-flight-destinations