Wet tires will probably never be used (unless enforced), even if the conditions are clearly full wet.
Teams are so greedy with staying on the inters so that even if some drivers pit for full wets, the race will inevitably be red flagged because someone staying on the inters will crash, which then makes you look silly for pitting for full wets a lap or two earlier.
Granted that they reinstated the positions of the previous lap so Perez is actually fine, but let Zhou crash one lap later and Red Bull would've been punished with Perez for doing the right thing for safety and to try and keep the race going.