T-Mobile is definitely not trying to charge you $10 more
twitter.com
twitter.com
There was first a "log me out" option then a lot of whitespace followed by the "Delete my profile" option which was not in the viewport by default.
I wonder how many people who set out to delete their profile didn't actually do so. It's definitely a dark-pattern.
The root cause is the design choice for the operating system to hide the scroll bar.
Yes, having a scrollbar would let people realize there is another option, but why is the viewport so small to begin with?
If you're willing to deal with an annual plan through an MVNO and buy through ebay(!), this is the cheapest I know of, starting at $30/year ($2.50/month) with 200MB: https://www.redpocket.com/plans/ebay
200MB is more mobile data than I use most months since I mostly use a laptop and/or wifi (I use mobile data for occasionally checking email or directions or browsing low-bandwidth sites like HN when bored). YMMV. They have larger plans too. I have their now-defunct $10/month plan on AT&T. Redpocket is not the greatest but it's legitimate as far as I can tell.