I'm confused by that website using $/mo as the unit to describe the cost of 1TB egress. How does the time component play into this? I would have expected the cost to be described in $/TB.
But it makes sense because the counters get reset each month.
So if you consume "101TB" over a year, distributed as 90TB in January and then 1TB per month... You could get hit pretty hard in January and have free bandwidth for the rest of the year.