If you're washing a sink full of bottles, you're probably doing it in water that's around 45° (which you had to heat up from, say, 20°) and you're probably using more like a cup of water (250ml) per bottle, not a liter. I mean, my sink won't even hold 20 liters of water. Even if that water isn't usefully warming up your house, we're still talking about (45°-20°)×250ml/bottle×1 calorie/ml/° for more like 26 kJ per bottle.
As for the steam, you only need enough steam to fill the bottle — perhaps one gram of steam per bottle, or a bit less. That costs you on the order of 600 calories, or about 2.5 kJ. Actually heating the bottle itself at 0.84 J/g/° will cost more than that; say that instead of heating to 73°, the minimum standard for food sterilization, you heat it to 150° with high-pressure steam. That's (150°-20°) × 200 g × 0.84 J/g/° = 22 kJ.
So, assuming batch autoclaves like you said, with much higher temperatures than needed, with people washing their bottles at home in the sink, we have an energy cost of 26kJ + 2.5 kJ + 22kJ = 50kJ per bottle, compared to the 200kJ you calculated to recycle it. And that's why glass bottle reuse is widespread, even if perhaps not in your neighborhood: it saves energy. In my neighborhood, it's basically universal. Beer is always bought in returnable bottles here, and soft drink glass bottles are usually returnable.
Why might it not be widespread in your neighborhood? Aside from the water-heating externality you suggest, I suspect that it's because you guys are spending extra energy to reduce labor costs, because labor is expensive where you are, especially when doing the labor means you have to deal with dirty, stinky bottles — even if occasionally.
On the other hand, basically anything you do with a plastic bottle — whether you return it for reuse or throw it away, both of which are common in my neighborhood — is going to cost a great deal less energy.
By the way, I'm really delighted to have a conversation here on HN that involves actual facts and calculation, along with careful consideration of the possibilities. Thank you for that.