According to upstream's NEWS file, lzo is optional since 1.18.4 https://gitlab.freedesktop.org/cairo/cairo/-/blob/7fd0cd0a9c0278c2b3d4c78087ca8481087b588b/NEWS#L6
Seems like it was optional before too. https://gitlab.freedesktop.org/cairo/cairo/-/merge_requests/590 simply exposed it as a meson switch.
Feel free to attach a patch or make a pull request on github. Looks like lzo is only used for cairo-script, so yeah, probably not often used.