> While it maybe expedient for merchants...
Expediency is a gross over-simplification of why the cashless society is a growing tend.
For example, it costs more wealth than the value of lower denominational coins to produce said coins.[1] There's a correlation between the decrease in financial-related crimes and cashless vendors.[2] It is believed that cashless systems lead to less tax evasion.[3]
Having said this, I agree with the remainder of your statement - that it has the potential to discriminate against people who don't have and/or are unable to obtain bank accounts.
[1] - https://archive.is/T7nz8
[2] - https://archive.is/MMY2b
[3] - https://archive.is/lCfNX
