system
Given the following post, respond as if you're commenting on Reddit:
human
Why do people spend up to 6-7 years to finish a PhD in the US, compared 4 years in the UK?

Not to knock anyone down, just an honest question. Is the standard in the US higher? Which is ironic considering the opposite is true for undergrad.
gpt
Other commentators point out the practical differences but should add specialisation occurs much earlier in the UK. Consider that you narrow to 3 to 4 subjects age 16-18, then to one at degree, plus a master's.