Why does a non partisan ballot not have the presidental canidates on them?

Question

I live in California

Answer 1

California has closed primaries... only people registered with a party may vote for that party's candidates in primaries.

Often, people will register with a party before an election, just to be able to vote in the primary, and then reregister as an independent after the primary is over... but I'm afraid it's too late for that now, with the primary next week.

Answer 2

A non partisan is straddling the fence and therefore has no say in either party until the final election.

Answer 3

I would assume that you're in a state with a closed primary (voters must be registered for a party to vote for that party's candidates).