I never hire nannies nowadays. Useless and broken I am afraid. The only really time I hire them is in San Myshino if the parent(s) want to spend time in the festivals that appear outside in their own area (no zoning required to attend). Then I like to have some adult with the babies and totts while the parents have their fun. I really don't like to take the toddlers to the festivals except the ones that are during the daytime and not even then because there is literally nothing for them to do except to dance and be underfoot.
I know that I can safely leave the the littlests in the apartments while the parents are downstairs in the streets but I really don't feel right about it so the nannies in this instance, are useable.
The gardeners in my game, do come but if nothing needs doing (I sometimes have my gardener Sims wake up early and do some gardening for skill-ups), the sceduled gardeners will tell my Sims that nothing needs to be done (with a notification) and leave without taking any fee.