If it really is that prominent, it could be some kind of de-essing (or de-tee-ing, I guess) type thing in the audio mix so they don't clip the mic, but also language just evolves over time. People tend to drop sounds in words, especially if they're talking fast. I don't think education level has anything to do with it lol. Also maybe for some it's an accent thing? I don't know, but as long you understand what they're trying to say I don't see the issue.