You're paying for the staff time to set up the lower-level infrastructure and keep it running at _least_ as reliably as if you had your own staff on bare metal, quite likely more so. (including scaling it when you need more etc).

It is interesting that they end up charging you this for _bandwidth_ though. Their staff time doesn't actually probably scale with bandwidth, but their prices do.

I think it's probably kind of a way of pricing based on a proxy for customer size, likely revenue, and ability/willingness to pay. Rather than as a % margin on actual costs.