The parliamentary system is a lot more volatile and competitive - if a leader irritates their party enough or is tipped to lose they're quickly challenged and voted out. In Australia we had 31 leadership spills from 2000 to 2015 and 5 prime ministers from 2010 to 2018.
Under the constitution, Trump doesn't have the power to unilaterally make trade policy (that is Congress's prerogative). He claims he does under a vaguely worded emergency powers law that clearly doesn't apply to current circumstances (we are not, or at least were not, in the sort of emergency contemplated by the law). (This goes to show that all such laws granting extraordinary powers to the executive during "emergencies" will eventually be abused by someone sufficiently unscrupulous.)
In a "real" parliamentary system, Trump already would have gotten a no-confidence vote.
Congress could revoke Trump's emergency declarations at any time. A measure to do this for Canada passed the Senate by 1 vote only. The House will not vote on it probably. Members of the majority party are more afraid they will lose their next primary elections if they oppose the leader than they will lose their next general elections because of the leader's policies. Those are not conditions to pass a confidence motion.
In Australia and Britain if the PM acts this wildly, the party steps in and replaces them. They call them party room coups, and everyone gets shitty when it happens, but they protect the status quo pretty well. It happened to 4 Australian PMs in a row and everyone was generally fine with it.
Also just look at what UK went through in recent years... PM operates on allowance of their party and in coalitions the other parties. Make too big moves and they are very quickly over the board.
A lot of people are comparing this to Liz Truss but in fact it's so much worse. The fact that the party not the people put her in charge means that there was much less loss of trust when they removed her.
Compared to if Liz Truss had been voted in by the public TWICE?
Many Americans thought their institutions protected the status quo pretty well.
In Australia the Liberal Party in changed the rules to require a 2/3 majority to remove a PM. In America blocking Trump's tariffs or removing him would require less than 1/3 of his party to vote with the opposition. They fear voters would punish them. How many Australian politicians voted for these party room coups knowing it would end their political careers?
The legislature passed a law granting the leader of the executive branch emergency powers. The leader of the executive branch invoked the law for actions the legislature did not intend arguably. This happened in parliamentary democracies also.
