It’s working differently. The customer places a signed by the satellite and libuplink orders on the nodes to download pieces from them, when they finish or cancel - the node will submit the signed by the node order with the actually used egress to the satellite and the customer would be billed on that amount and the node will be rewarded on that amount.
See
and
So, getting a payment from the customer for the used egress is not an issue, as confirmed by several people above.
The real issue is clearly described by @Toyoo - this order must be signed by the satellite too, to apply ACL and enforce limits.
See
@snorkel The satellite uses cache for the nodes selection, so I do not know, what issue do you want to solve?