The 50% rule is an average of a large number of rentals over a long period of time. It is possible to do much better for a period of time. Or much worse. Several categories I see missing from your list:
Utilities-most places there are some type of utility expenses. Water/Sewer/Trash is common for landlords to pay here. If you have those put onto your tenants, you would do better than average. Even if you don't pay any utilities, on average, landlords do.
CapEx-Your roof may only be 5 years old and last 25-30 years but the 50% rule assumes that you are putting 1/30th of the cost of a new roof away for eventual replacement. Water heater, furnace, air conditioner..... You may never actualize the expense of a new roof, sewer line, plumbing lines, tuck pointing etc depending on the timing of your ownership. Again, this is an average of a large number of units over a long time period. I think someone on here said something along the lines of, "Don't mistake deferred maintenance or unfunded CapEx as profits."
Evictions/legal-They will happen. Again, an average. You may be a tenant screening superstar. My one eviction they drug out as long as possible by asking for a jury trial (2.5 months). Then, as soon as it went through and I could legally get the Sheriff to serve the eviction notice; Ferguson/Michael Brown erupted in St. Louis and they weren't serving anything for 2 weeks as all manpower was dealing with that. Then it took another week to get through the backlog and then the tenants still had 10 days to get out after that. Sometimes shit really does happen.
Insurance-Umbrella or liability insurance, not just on the properties.
Business expenses-cell phone, internet, mileage, forms, printing, entity setup, legal fees, permits, etc
Lawn service/snow removal
Other expense differences are:
Taxes-looking in my metro area, I see municipalities where property taxes range from lower than 1 months rent (<8%) to nearly 2.5 months rent (~20%). So if you're in a lower tax area, you should do better than the average.
Vacancy-I think 8% should be a minimum as that is 1 month of lost rent on a turnover. You're not off much at 7% but along with the vacancy expense of not receiving rent, usually you have added repair expenses of painting/cleaning/repairs/replacement/utilities/rent up fees/showing between tenants/first month of new tenants etc. So that tends to be an all or nothing expense. You can label those expenses differently (painting between tenants labeled as a repair or a vacancy expense). No vacancies that year? You got a nice bonus.
Repairs-One tenant tore the upper cabinets off the kitchen wall and 2 drawer fronts were missing from the bottoms so I had to replace (and I chose to upgrade) the kitchen as I couldn't match the fronts. They also took a machete to the kitchen floor (at least that is all I can imagine what happened to tear it up that bad). Those repairs/upgrades are about 60% of the year's rent. Again, it's an average.
I'm probably overlooking something but these can be added to your list. I have experienced less than 50% in expenses overall myself but I still use 50% in my projections so that I am covered by the unexpected as well as the what should be expected but usually isn't (CapEx).