Why are Japanese cars considered to be more reliable than US or European cars?

I'm currently car shopping for a recent model year sub-compact crossover SUV.

I was perfectly willing to evaluate vehicles from all manufacturers. Part of my search also includes looking up the available models on JD Power reliability ratings, consumer reports, and other testing agencies, and what I'm seeing is that the US-made vehicles in this category have reliability ratings that are significantly worse than the reliability ratings for the Japanese models.

Since I don't have the money to go out and buy one of everything, I'm forced to have to accept the findings of other 3rd parties who do the evaluations.

So to answer your original question: Japanese cars actually are more reliable that US cars based on the conclusions of objective test results. There's no "considered to be" about it. It's not a matter of subjective feelings on the issue.