Several prisons I was housed in had the toilet in our cell, a couple feet from our bunks. We used a towel draped over the seat as a lid. This was typical for a 2 or 3 man cell.
Yup-I had that in my brief stint at the Yazoo City Maximum I was in. It had all the fun trappings of Dante's Inferno: armed guard towers, electrified fences, not a bird within miles. And that stainless steel toilet/sink right next to a thin mattress on the floor.
breakfast at 4:30 am, as I recall.
The toilet seat is typically cleaner (in terms of bacteria) than the office desk. Certainly aerosol contamination is a risk, but that can easily be solved with a protocol of leaving the lid closed. And that's all assuming that bacteria are outright bad; it's becoming more apparent that too little exposure to bacteria is dangerous as well (can lead to auto immune disorders). Obviously I'm not suggesting living in faeces, but a bit of pragmatism can make something like this not a problem at all.
And it's easy for a kitchen without a toilet attached to become disgustingly unsanitary.
Especially not if it's your own poo. You might keep reinfecting yourself with some bacteria or parasites that would otherwise have a slim chance of staying in the body, but the human immune system is pretty well-equipped to handle that.
Having your own toilet in your own kitchen is probably more sanitary than separating toilet and kitchen, but sharing them among multiple people.