Expanding on this:How much is that in percent? Because from what I've read, the charge point reads what it pumped out, while the car reports what went into the batteries. Losses in between may occur.
up until last year there was no certified DC meter anywhere to be found - because it simply wasn't needed (you can still measure DC energy fairly easily, but not necessarily correctly...). those were only developed and certified to conform to german EICHRECHT (metering law) requirements for DC charging stations (wohoo), and while the market for charging is growing rapidly, in the grand scheme of things this is still very much a niche case, so those meters are super expensive, in contrast to AC meters, as they're used on every level of the AC electricity grid. the metering law would not allow the losses inside the AC/DC conversion and the charger to be calculated against the customer when measuring the AC-energy going into the charger (which was mostly done up to this point, i.e. the customer would pay for all conversion losses).
I would very much expect, if for cost reasons alone, for most/all DC chargers outside of germany (and maybe austria) to still measure AC energy and bill based on that. in germany, an exemption that was granted for a certain grace period allowed AC measurement, but required a 20% (!) deduction in the amount billed to the customer.
The losses on the way to the battery are also a factor, of course, but to be fair to the CPO, why should they not be billed? The CPO bills whatever energy leaves their station (plus maybe 5m of cable, which is not too bad tbh) - everything behind that depends on the customers car and behavior (e.g. cold-ass battery will just dump huge amounts of energy into heating that thing).
to be fair: this very much also happens for me when I charge at a tesla supercharger. the amount billed (and counted up during the charge) is always higher by a considerable margin from the energy delivered as shown in the car multiplied by the charging tariff.