As far as hiring managers, it is a gig a lot of retired folks do. Or, folks who are partially disabled. Yes, finding reliable people to do this is difficult. Some stories of the high-jinks some of the managers have done. There are rules about what needs to happen to units that have been taken over due to not paying the rent. As most folks know now, they are usually auctioned off. Some managers were going through them first to grab anything they might want. There is the bookkeeping aspect. Some people are better at it than others. This is not a high dollar job, but there are high-dollar expectations on ability to handle money and honesty. It is a people job, you deal with the public in all their glory. So, the owner is asking a fair amount of the managers and not paying a whole lot.
Finding too assistant managers, to take over the days the managers are off, is an even dicier deal.
This can be a perfect job for the right people. Place to live, utilties paid, not a lot of stress when life is going as it should (no bodies/stolen vehicles, etc in the units). Assistant managers have a low stress quiet place to hang for a weekend job, which is great for students. However, it is good to look at it from this perspective going in as an owner, and not just the real estate and construction costs.