Anyone that says "bass is easier than guitar" has no idea what they are talking about.
I've been a musician for more than 25 years. I've played, in a practical sense, guitar and bass for years upon years.
They are two different instruments, with two completely different jobs.
When composing music each instrument must be written for differently.
Speed and agility across the fretboard does not make guitar harder. Just by the fact that the guitar fretboard is smaller, and guitar strings are smaller, makes the guitar much easier to be an agile speed demon on it.
Bass is the rock and foundation. You have to know what you're doing to set a good foundation. And jazz bass is a whole nother story.
Don't compare that which shouldn't be compared.