A European PhD is recognized across the United States and will qualify the holder to work as a professional in the U.S., provided it comes from an accredited college. That said, European PhD holders often lose job opportunities to U.S. PhD holders. There are advantages to getting a PhD in the U.S.
In a vacuum, a European PhD is just as valuable as an American PhD and vice versa. In practice, America spends more money on professional research than Europe, and as a result, has more influence in professional research. This means that American PhDs tend to have an advantage in the job market.
Academia is appealing because it often provides better job security, and the range of research opportunities is much wider. Industry is often much better funded, paying researchers more and giving them better resources for their research. In most cases, the decision really boils down to the job offers you get.
One of the main reasons to choose academia over industry is that you have a lot more control over what you research and/or study for your job. Another driving motivation is the desire to contribute to educating younger generations. You might also prefer the academic environment and the chance for tenure.
It is possible to fail a PhD defense, and it does happen every now and then. For the most part, this only happens when a student defends without sufficient support from their advisor. Either the advisor failed in their role, or the student blatantly ignored the advice and defended before they were ready.
Rowan Atkinson does not have a PhD. He does hold a bachelor’s and master’s degree in electrical and electronic engineering, and he was even admitted into a PhD program. He dropped out of his PhD studies in the first year to pursue acting full-time. He is also an Honorary Fellow at Oxford.
The big difference is in the path to obtaining the PhD degree. In the US, a bachelor’s degree is usually required to get into the PhD program. While you can’t normally apply to the PhD program in Europe without a master’s degree. Both PhD degrees in these two regions, however, are recognized in either region.
The biggest difference is that PhD programs in Canada usually require a master’s degree before you can apply. This makes the programs two years shorter, on average. Additionally, the US is a much bigger country with a lot more opportunities, and PhD outcomes tend to be better in the US as a result.