With my first prepaid phone in Germany texts did cost 0.49 € per text. So I did not use them super often. Years later around 2011 that price had decreased to 0.15€ and I was texting friends a lot during uni. Around the same time me and my friends got our first smartphones with contracts for 30-40€ per month that included a small bit of data (below 1Gb). Texts still did cost 0.15€, but the data for a WhatsApp message was in the low kilobytes. So a lot of people switched to WhatsApp
With my first prepaid phone in Germany texts did cost 0.49 € per text. So I did not use them super often. Years later around 2011 that price had decreased to 0.15€ and I was texting friends a lot during uni. Around the same time me and my friends got our first smartphones with contracts for 30-40€ per month that included a small bit of data (below 1Gb). Texts still did cost 0.15€, but the data for a WhatsApp message was in the low kilobytes. So a lot of people switched to WhatsApp