Remember the target demographic though. These are people who presumable require internet access first and foremost simply to access some basic online data; not to stream youtube/netflix.
I'd wager these people still want to be able to view pics, watch videos and download music like anyone else.
And in any case, what does "basic online data" even mean today when you consider the size of the average javascript-laden site.
It's almost unbelievable how disconnected from reality we've become if we think that 500 MB per month is useless. Ignoring gaming and media, 500 MB is more than I use per month on my phone, and I use it a lot every day. I remember when the web first became a thing and I was first able to contact people using IMs and emails. It was a huge, life-changing deal. You need to think back to your own experience with this, assuming you lived through it anyway. The difference between no Internet at all and 500 MB of Internet per month easily captures 95% of the total value that the Internet actually delivers to your daily life compared to the difference between 500 MB and unlimited.