Being paid at 2/3 base is technically not "unpaid" and it's better than most other tech companies, but it's hardly laudable. They're basically saying your life (literally--the time you spend on-call is time you never get back) is worth less when you're working for them, but outside office hours.

I will probably never cease to be amazed at how naive software engineers can be. It's like the relatively high base salaries act as bedazzling enchantments that turn off parts of the rational brain.