Do you refer to fiat payments? If so, then you do have a fair point, but in this case it would be great if people were given the option to either choose to pay with fiat, or with Bitcoin. It would make the most sense as well.

At the end of the day, it's all about generating income through these vending machines, so in current times it would be an utter waste of invested capital if such machines aren't accessible to all payment fields.

It's basically you saying no to potential revenue, which is not how things work in an economy. Bitcoin isn't yet at such a stage to completely rule over as payment option, and I don't know when and if it ever will.