I think the goal is to make it as pleasant as possible for them in the worm bin, so they don't want to escape.

Even with (what I think to be) ideal conditions I still have one or two escapees every couple of weeks. Outside of leaving a light on them at all times, I don't think there is much I can do about it.

I suppose had the bin been outside those brave ones would have been the ones to make it across the great no-worms-land to start a new colony somewhere else, Insuring the species continued survival. But in the kitchen my Tile hampers their efforts. :-)

SRD

I have a stackable wormary. when I put another level on I do not put any coke cans in between I just rest the top container on the casting/scraps and then stuff newspaper in any gaps. When you get to take the bottom container out the old newspaper will be reused or go into your wormary.

I have stackable worm trays and I keep an old aluminum baking tray filled with water underneath the bin. Haven't come across any escapees so far (*knock on wood*) but when I tried vermicomposting the first time (this is my second attempt) and had escapees, the water-filled baking tray came in handy.