At the end of the day it's a comedy show not a news show and his job is to make people laugh. You can't make people laugh with jokes about insider domain knowledge only possessed by experts.
If you consider the constraint that Last Week Tonight is primarily a comedy show themed around important newsworthy issues rather than an investigative journalism show it's hard to imagine it done any better.
If you consider the constraint that Last Week Tonight is primarily a comedy show themed around important newsworthy issues rather than an investigative journalism show it's hard to imagine it done any better.