Before iPhone or Android existed, Blackberry was very popular with teens because you got unlimited messaging on Blackberry Messenger included with the data plan you got with a Blackberry.
Eventually there were cell phone plans where you could add unlimited SMS for an additional fee regardless of what phone you used.
By the time the iPhone rolled around, all the American iPhone plans included unlimited SMS messages without an additional fee.
I guess it depends on your terms. I had--I think--a 2GB per month data plan (which was actually fairly reasonable for mobile at the time) and later went to "unlimited" but I was still paying something like 10 cents per text for a time. I didn't text a lot so I just paid a la carte until I changed plans.
Communications charges have changed a lot over time. I remember when long distance calls were something like $1/minute.
I can remember Verizon being sued because they forced handset manufacturers to disable Bluetooth for file transfers, because Verizon used to charge you money every time you transferred photos to or from your phone.
iMessage was released 11 years ago now. Can’t blame Apple for what not considering what the toddlers of the time would eventually do with the technology.
But wasn't cellular data priced similarly extortionately back then?