So you're telling me that, not only are federal elections decided by states rather than votes, but each individual state has their own set of laws to prevent you from appearing in the ballot? And it's somehow still fine because "you can just do a write-in vote"?
My favourite one is the Texan one, where you need to have gotten boatload of votes in order to appear on the ballot.
For a registered political party in a statewide election to gain ballot access, they must either: obtain 5% of the vote in any statewide election; or collect petition signatures equal to 1% of the total votes cast in the preceding election for governor, and must do so by January 2 of the year in which such statewide election is held. An independent candidate for any statewide office must collect petition signatures equal to 1% of the total votes cast for governor, and must do so beginning the day after primary elections are held and complete collection within 60 days thereafter (if runoff elections are held, the window is shortened to beginning the day after runoff elections are held and completed within 30 days thereafter). The petition signature cannot be from anyone who voted in either primary (including runoff), and voters cannot sign multiple petitions (they must sign a petition for one party or candidate only).
In Democratic America, you can only win elections if you've already won the elections.
My point is that we know what introduces sample bias, that's it. it's already gamed to the point that it's hardly worth talking about.