What made equal-length hours move from specialist astronomy into ordinary daily life?

Answer: Mechanical clocks spread them

Obelisks alone fixed them — Obelisks were important early shadow instruments, but they did not by themselves create equal modern hours. Shadow-based daylight divisions still changed with the season. They are part of the origin story, not the standardization mechanism.

Mechanical clocks spread them ✓ — Correct. Hellenistic astronomers helped formalize equal hours, but everyday life needed devices that repeatedly displayed them. Mechanical clocks appearing in medieval Europe made equal hours more public and habitual.

Water clocks spread them — Water clocks were important because they worked when shadows did not. But the broad public habit of equal hours needed displays that repeatedly regulated civic life. Mechanical clocks, not water clocks, made that standard feel ordinary.