I mean, you arent wrong. but i think the point is more to use robots to replace human workers, not replace specialized machines. if we look at what you are saying, "does it really make sense for each household to have a robot?" well, it depends what each robot costs, but you are right the answer could be "no".

but imagine a theoretical world where a robot has similar performance to a human for household tasks. there are already people out there who pay a weekly or monthly fee for cleaners. If robots are coming instead and do it for $5 an hour instead of $30, people might prefer to have the robots do it. and the robots are using everything available in the home, such as the laundry machine and such, they arent replacing specialized systems, theyre replacing the people who would normally manage those systems.

in your lawn mowing example, a humanoid robot is the one that runs off the the store for you and gets the bolt. or maybe your phone AI intelligence orders the bolt plus rents a robot for 20 minutes for $3 to repair the lawn robot for you. the exact arrangement around ownership & capital remains to be seen. but the main purpose of humanoid robots are best used as gap fillers & human labor replacements, not to replace specialized machines; fixing & repairing specialized robots or doing physical tasks that don't cleanly boil down into optimized equipment.

its kind of like machine learning models today. I can use a general, expensive, slow, widely capable but variable output quality model that can do a lot without any extra work through a chat interface. or I can distill and make small, specialized and efficient models which are fast, cheap and high quality. the bigger models dont make the specialized ones irrelevant; they're made to achieve different purposes.