[caf]

Sadly, most people vote based on who they want as prime minister, and they put little thought who is running their riding.

This is entirely rational, though. The local MP has two primary functions - one is to vote on legislation, and the other is to support a particular set of MPs to form the executive government (personified by the Prime Minister, because the PM usually gets most of the say in who makes up the remainder of the executive).

Both of these are important, but the choice of executive normally has far more effect on the day-to-day running of the country (and the executive mostly gets to set the legislative agenda anyway), so it's no mystery why people tend to focus on the choice of executive when deciding which local MP to vote for.