TL;DR TOS are quite refreshing! Of course I'd be interested to hear if this opens them up to any liability due to the summaries inherent imprecision... Can any lawyers chime in on this?
Before using any of the 500px services, you are required to
read, understand and agree to these terms. You may only create
an account after reading and accepting these terms. The column
on the right provides a short explanation of the terms of use
and is not legally binding.
Obligatory IANAL, but that explicit statement probably covers them from any potential liability from providing summaries.