Why can only Canada’s House of Commons introduce bills involving taxes or public spending?

In the Canadian parliamentary system, the House of Commons is the only body permitted to introduce bills regarding taxation or the expenditure of public funds because it is the elected chamber of Parliament.12

This requirement is rooted in the principle of representative government. Because the government of the day must maintain the "confidence" of the House of Commons to remain in power, the authority to initiate financial legislation is reserved for the members who are directly accountable to the Canadian electorate. While the Senate must still pass these bills for them to become law, it is an appointed body and therefore lacks the democratic mandate to originate legislation involving the imposition of taxes or the spending of public money.12