@Eric6984 We have Hot Tubs at our rentals. Yes you can get more money but they are expensive to run with the electricity prices at the moment and also the upkeep and chemicals have to factor into the running costs too.
The other thing to note is they do need checking everyday and yes we have had times when they have broken and needed repairing. You also need to leave enough time between guests for cleaning and refilling and any repairs that might need doing. They are a lot of work. As we are onsite hosts it is not so much of a problem though.
You also have to be very clear with your instructions for the guests. We have quiet times as the jets on the hot tub can be noisy for those around. Also the amount of people that would if they could sit in them for 2 hours with the jets running are amazing. And then you get the guests who decide it is a good idea to get in with shampoo in their hair and turn it into a giant bubble bath !
The big thing is the word "shared" I do find if the guests haven't read our listing properly the questions they ask is "Is the Hot Tub private" I don't think people like the idea of sharing a Hot Tub and your price will have to adjust because of this. Also will you have set times for each Tiny Home or will it be a a first come first served situation ? Personally I wouldn't do a shared Hot Tub situation but other hosts might do this and be able to advise more.
For us I am not sure whether being able to charge more outweighs the cost of running them but I am certain that we are booked more because of them.
Hope this helps.