No mold here. And I even cover half of that opening with a moist paper towel to up humidity when she's showing signs of shed.

I think your wife is basing what she says on figuring the cage will remain covered...but it won't. You open it for a few minutes at least every other day to spot clean and change water, not to mention to handle your snake (except the two days after feeding of course). This fact, and the fact that you NEVER soak the substrate but just mist it if you need more humidity, means that the hole for the lamp is adequate ventilation.