I start to freak out if the weekly bill for any given sim goes past a thousand or two...
Keep them in pretty small low clutter homes with a lot of solar panels and a dew collector and if I can pull it off-grid. My 'real world' home is "electrically off-grid" as Sims defines it with solar and battery backup and excess sold to the grid (true off grid would give me no ability to sell back, but you can sell back in Sims if you have stored energy so thus - I meet the Sims 4 definition).
I'm not sure how I could even manage to have some of the bills some people are mentioning. But I guess if you put out enough stuff that will do it.