That is a very good question. And there are many good reasons.
You are right in that it is much easier 'lowering' the voltage in an AC home component than it is to 'step up' the voltage in a DC auto/marine component (especially since transformers do not work in the DC realm). And you have an endless supply of AC power in the home. There is no 'at rest'.
So let's say you are placing a full and biggy 7.1 home theater system along with whole house distribution, including 4 to 8 outside speakers around the pool and pool house, etc. in a converted closet. That either constitutes a ton of amplifier channels or some really huge amplifiers with a matching multi-tap autoformer. Now the 15 amp service capacity is way beyond toast and you place your expensive electronics at risk from sagging voltage. Even twin 15 amp services will get challenged. So enter fullrange Class D for the whole house distribution.
I have some pretty big Sherbourne amplifiers in home that are Class H. So higher efficiency has caught on in the home too.
Several editions ago in Absolute Sound they had a very long feature article about Class D with just about every top amplifier engineer in the home Hi Fi biz. Yep, including the tube and Class A pipe smokin' guys with twead jackets and suede elbow pads. And, you don't get that type of attention unless the technology has come of age.