They do report that number. It's available on the dashboard every time you charge the car, as you stated in your original post. It includes both charge and discharge efficiencies. You can make the argument that Tesla is not as transparent as they should be, but the number is available to those that want it.
They don't show that number where they should: in the consumption and in what Tesla calls Total Energy (which should be called Part of the Energy).
And, additionally, that number
DOES NOT show you charge efficiency: you pull 55 from the wall, and 50 enter the battery. The car shows you the 50 at the end of the charging session. You NEVER see the 55 anywhere in any of the car's indicators. You can only see the 55 if you install an energy meter (like I and others have done)
Then, as soon as you disconnect your charger plug, the info regarding those 50 is gone for good. You'll never see that again, unless you connect to the canbus and look for the Lifetime Total Energy Added for the battery.
And then, you drive to empty, pulling 45 from the battery, and the car will only show you a consumption of 45, both in the Total Energy, and in the wh/mi indicator.
If you only look at the car's Total Energy and wh/mi indicator (like a normal person, not us geeks at TMC), you'll NEVER know you 50's and much less your 55's. You'll mistakenly think your car uses 45 to do X miles.
Like ICE cars evolved to the WLTP cycle, I'm certain some day EVs will be forced to show their users their real Total Energy consumption.
Until then, we'll have to live with a Partial Energy consumption indicator, which 5% of the users know omits charging inefficiency and vampire drain, and 0,01% of the users know that it also omits discharge inefficiencies.
