Why do MMS messages cost so much or at all

I can send a pic via whatsapp or viber or email for free in my data allowance.

Does anyone work for a phone company that can explain why a MMS cost up to 35 cents when data is data.

This is less of an issue with the 3 apps mentioned but I am sure people are still getting caught out.

There is no reason other than profiteering.

These days, thankfully, most people use messaging apps.

FB Messanger, Messages (Mac/iPhone/iPad) are also free as are monthly web text allowances from some phone companies