This is true, but something about being an Electronics Engineer makes you want to check. (I didn’t even trust Philips to get it right, but they did.)
I didn’t go into detail, but simple Dashed/Solid line doesn’t tell you the whole story. Those simple wall warts are not fancy switch mode, or even old school rectified. I measured 14VDC unloaded, which I can probably guestimate in experience, to be a 9VDC loaded reading.
The actual reading on wallwarts are generally untrustworthy, unless its a thing from Samsung or apple, where the circuitry are what you would expect (switched etc).