So, if they are vaguely mammalian, then they reproduce, and as such, they also have plumbing involved with eating and drinking and the opposites of them fine functions. So, that means that they have to have doctors and nurses and nannies and charwomen and janitors and plumbers and condom testers and garter belt developers... hmm...
and dentists! Yes, there must be DENTISTS, mustn't there! Of course there be.

So, anyway, as I wasn't saying, just yet, if the evil or just very intent ancients are or were going to build some intricate labyrinth of mythical proportions (or half-portions, for the dietarily conscious) that is destined to lay almost dormant for seven or eight centuries or millenia (um, i, or ea) and then spring to life and crush the hero or heroine the entire damned thing was designed to deal with in the first place, all those many, many years ago, and they are or were going to go to all that expense and effort to ruin the real estate market in their vicinity and make sure that sewer systems would either be impossible or incredibly leaky, then why wouldn't they go the extra cubit and create or install some people to take care of the immense investment and replace the lightbulbs or the torches in the sconces?

It's like the Geniis in the bottles. Who in their right mind would imprison an immortal minion in a piece of crockery or glass when they could magickalally chain such a powerful and incredibly bored entity to a job as a maintenance man in a secret underground labyrinth of stone, iron and tricky clockwork with pointy teeth and sliding walls to be taken care of in perpetuity?

So, as it has been suggested, if the only criminals we hear about are the inept ones, and the really competent ones are still doing business without the public eye on them, then is it possible that somewhere in the depths of the modern world, the Guild of Immortal Maintenance Workers is doing their job with alacrity, precision and care and the only labyrinths and dungeonous traps for holy heros that we know of and are penetrated and destroyed by these costumed or oddly named weirdos are the ones were the Guild of Immortal Maintenance Workers decided to walk off the job because of failed negotiations with the management?

So maybe the reason why all the known secret labyrinths and ancient mechanisms of death are all so samey and boring is because all the really great ones are still being hidden away from the eyes, minds and imaginations of the FANBOYS and their fanfans and the fanfanfans.