Well perhaps it's my reading comprehension that's the problem, but this is what I read on page 84:
Earn doesn't mean that this is what the characters are supposed to receive?
Well, either we both failed our reading comprehension or this whole section is half-gibberish. I'm going with the latter!
From DMG page 82, under "Evaluating Encounter Difficulty."
This adjusted value is not what the monsters are worth in terms of XP; the adjusted value's only purpose is to help you accurately assess the encounter's difficulty.
And then, from page 84, under "The Adventuring Day" (including what you quoted above):
For each character in the party, use the Adventuring Day XP table to estimate how much XP that character is expected to earn in a day. Add together the values of all party members to get a total for the party's adventuring day. This provides a rough estimate of the adjusted XP value for encounters the party can handle before the characters will need to take a long rest.
And then the table has "Adjusted XP per Day per Character."
So, basically, contradicting statements on the part of the DMG, but I believe that the intention of this table is
not to give the amount of XP a character should earn. Furthermore, it is my experience of actually adding up XP for encounters, even including XP for non-combat encounters, that we never once hit these numbers in an adventuring day, no matter how challenging the day. You'd have to fight only solo monsters. (Which are, admittedly, xp handouts.)
The most continuous game-time I've had in a 5e campaign was probably a campaign that lasted about 9-10 months and met weekly (obviously with some weeks off). When we finished, I think characters were 8th or 9th level. That was encounter-based xp awarded, basically, "raw".