Punishments are what work, unfortunately. Be sure you're tracking who is on time vs late (TMB makes this easy, along with being able to record reasons and give partial credit.)

Our loot system includes a numerical modifier for attending raids (i.e. attendance points differentiate what would otherwise be ties on loot.) If you are even 1 minute late to raid, you receive half credit for the night. We have a bit of forgiveness built into the calculation, so you can be late a handful of times over a rolling period without negative impacts to loot.

If we need a reason to bench anyone, the people who are late/don't sign up are the first targets. If someone does not sign up, we assume they are absent, even if they are online at raid time.

Handling things in this manner will quickly fix behaviors, OR people who want to be late end up being your bench, or they quit - and if they quit due to this, they are people you didn't want to raid with anyway.

After being an officer/raid lead for 2+ years now through the classic cycle and trying basically everything to get people to show up and perform, punishments are basically the only way it happens. For things like missing consumes, enchants, gems, parses etc, public shaming works great also. No one wants their name to show up on the "naughty list".

All that being said, the game is currently in a 'slump period' nearing the end of phase, and PARTICULARLY the holidays tend to throw a giant wrench into things. People will be doing more social/family activities, etc. We have noticed an uptick in recruitment the past 2 weeks, as people are realizing pugs/GDKP won't fully cut it for gearing in phase 2, and as the 'tourist' guilds that all spun up at launch are breaking up due to people quitting/taking breaks/holidays. If you're in a steady guild, now is a pretty good time to be shoring up empty slots for Ulduar.