First of all, it seems highly unlikely such a distribution of red and blue votes would occur. But more importantly, blue is a majority of every 3x3 square - why shouldn't it win every district?
Because we are supposed to have a representative government. If there's 55% Blue voters and 45% Red Voters, you're supposed to ideally have 55% Blue representatives and 45% Red representatives.
The example is a counterexample of this concept. Instead of 55% Blue / 45% Red split, the map as a whole becomes 100% blue. This is almost the very definition of "Tyranny of the Majority".
Maryland is an example of a highly gerrymandered state (towards Democrats, although there are many Republican examples too). Maryland voted 60.5% Clinton / 35.3% Trump, which suggests that they have (roughly) 2 Democrats for every 1 Republican in the state.
However, due to the significant gerrymandering in Maryland, there is ONE Republican and SEVEN Democrats in the House. That's certainly not fair towards Republicans who live in Maryland.
EDIT: Apparently North Carolina is the Republican example to talk about, in case you want some "balance".
There are actually more extreme examples. Consider, Hillary Clinton got 90.9% of the DC vote Trump got 4.1%, I am not sure how you could slice up DC to get 10% Republican representation.
In Maryland's case it might be able to make 2 districts Republican, but that's assuming a very concentrated geographic minority which may or may not actually exist.
IMO, If we really want proportional representation then we should use a proportional system.
DC is a single city and doesn't even have one representative in Congress (Okay, they nominally have one. But she's non-voting so.... that's not really useful). They're technically a US Territory and have no more power than say Puerto Rico.
So once again, if you're talking about US Representatives and Voting Districts, it only makes sense to talk about well... Voting Districts. Name me one US State with 80/20 split and more than 1 US Representative. Ultimately, your hypothetical doesn't exist!
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That's the cool thing about politics: its real. There's no need to make up hypotheticals when we can just draw from the real world.
FYI: the discussion at hand is about US Representatives, and not about the Electoral College. Washington DC is therefore irrelevant, as it has no representatives. Washington DC does get 3 Electoral college votes, but that has nothing to do with Gerrymandering.
There's a variety of states who have "Representatives At Large", such as Wyoming, which are basically immune to Gerrymandering. The population is so low that Wyoming only gets 1-Representative, so the entire State is the whole district. There's really no "fair" way to cut up a single Representative (its all or nothing), but that's mostly due to the very low population of these states.
Basically, Gerrymandering can only be an issue in a state with more than 1 Representative.
These rules are not limited to National elections. State elections are also based on redistricting. DC is part of the US and has District Elections so these rules will apply to it.
It seems to me that probably the outcome of an election should mainly be determined by the decisions of voters, not mainly by how the voting districts are drawn.
Imagine that a few voters in each district change their minds, some from each party switch to the other. Even if the overall effect is a very slight swing towards red you could still end up with all the districts going to red. Or with the same swing but distributed differently you could still end up with blue winning (though not by as much), even though it had fewer total votes.
So it's not about what should happen in any one particular snapshot. That's just a single example. It's about how well the outcome of a series of elections should reflect the wishes of voters as a whole. I'm not a big fan of proportional representation, it has often lead to small minorities gaining kingmaking powers, but I do believe that the objective of electoral districting should be to produce results that are likely to fairly represent the wishes of the electorate.
Blue is indeed a slight majority of every "3x lattice"-aligned square. But if you take the top left square and shift one down and one right, you'll see that in fact red wins that 3x3 square decisively: 8 to 1.
> why shouldn't it win every district?
Maybe you think it should, but whoever drew the districts would run afoul of the newish gerrymandering measure the Supreme Court is considering.
Because we are supposed to have a representative government. If there's 55% Blue voters and 45% Red Voters, you're supposed to ideally have 55% Blue representatives and 45% Red representatives.
The example is a counterexample of this concept. Instead of 55% Blue / 45% Red split, the map as a whole becomes 100% blue. This is almost the very definition of "Tyranny of the Majority".