> Why can the governor general replace a prime minister who has a majority?

It's one of their constitutional rights. Their purpose is to act as a surrogate for the Head of State (currently Queen Elizabeth II) and the role was designed to mirror the process of the UK's Head of State -- the Queen picks her ministers and in theory doesn't need to choose the leader of the party with the largest number of seats.

Do I think it's a system that should be changed? Yes, but this is complicated by the need for a mechanism for double-dissolution (which cannot be automatic because it could then just be gamed to re-trigger elections).

> Why did the citizens reward and vote in the party who pulled those election tricks.

As is usual, propaganda. The laundered $24m wouldn't have been used to buy toilet paper.

> Why would you blame the US but not bother to change the laws? This can happen again.

Given that the US triggered and orchestrated the constitutional crisis in order to further their own foreign policy (which was confirmed by President Jimmy Carter to have been the case when he vowed that the US wouldn't do it again), I think it's entirely fair to blame the US.

In order to change the role of Governor-General you'd need a constitutional amendment. To say that it's effectively impossible to get a constitutional amendment passed in Australia is an understatement (only 8 amendments have been passed, out of 44 attempts in the past ~120 years -- and most of those were passed soon after Federation). One of those failed amendments was to switch Australia to a republic model which would've replaced the Head of State and Governor-General with a President -- but the overall set of rights given to the President would've been the same.

It should also be noted the inclusion of double-dissolution in our Constitution was somewhat controversial at the conventions during drafting, but was eventually agreed to be vital if the Senate was to have the powers it currently has. So we would need some mechanism to avoid deadlocks, and the lack of obvious alternative solutions to this problem results in most proposals just keeping the existing system but changing how the Head of State and Governor-General are elected.