I think it's generally pretty silly when people refuse to use public toilets.
It's not that I don't understand the anxieties! On the contrary, using a toilet causes me much consternation. It's very uncomfortable. There are a few reasons for this.
1) I'm convinced everyone can hear me pee.
This is the worst in stall-type bathrooms. I have been informed that I pee loudly. This is because I don't like to waste time on the toilet, so rather than just relaxing and letting it dribble out (as I've been told is the proper way for a lady to go) I just... push it out. Ever since I was made aware of this particular fault of mine I'm always convinced that the person in the next stall is thinking "What the- who let the race horse in here?!".
The logical side of my brain tells me that there is no way this is the case. The crazy side of my brain screams and tries to run away. Of course it's too late. The habit has been formed since childhood. I have been unable to teach myself to "relax and dribble". This anxiety follows me to the one person bathrooms at work, my friends bathrooms and even my own if I have someone over or if my roommate is home. Also, the same multiplied goes for number twosies.
2) I don't think people actually wash their hands.
I walked out of a stall one night right as a girl turned the faucet on. She didn't notice me because it was a creepy mirror-less bathroom (don't get me started) and I was behind her. However, instead of washing her hands she texted on the phone. She then left while I was washing my hands, without ever washing hers. She either just likes ambiance for when she texts, or she turned the sink on to pretend to wash her hands so she wouldn't have to actually do it, but no one would think she hadn't.
Now I am paranoid about people not washing their hands. When someone walks out of a stall before me, or if I'm waiting outside the bathroom at work I can't help but strain to hear the sounds of hands under the water, disrupting the flow. I try and listen for the light thunk of soap being dispensed from the dispenser. This is intrusive, and I know this. That's why I always act like someone is listening and I'm as loud as I can be when I'm washing my hands.
3) I don't always go into a stall to go to the bathroom.
Sometimes, like when I'm at the gym, I go to a bathroom stall to change. This is because unlike other women in the locker room, I have no desire to bare my breasts and ass for all to see. I'm far more comfortable changing in privacy. This usually isn't a bit deal until I get all changed, leave the stall and go back into the locker room only to realize what it looks like.
All other people are probably noticing is some girl leaving a stall and then going to use public machines to work out. Since the toilet automatically flushes they don't know that I didn't use it! I've gotten glares, comments and whispered conversations. I'm just guilty by association. Sometimes I just wash my hands so people don't think anything of it, which is annoying because it's a waste of time.
4) I hate cheap toilet paper
This isn't always a problem, like at work or at home I don't have to worry. However whenever I'm at school, at a speech tournament or any place that has a high volume of people using the facilities the toilet paper is almost always really cheap. It might have to do with saving money, or being "green" by getting the single ply instead of the double. Of course that whole concept is idiotic. If someone needs to use 2-3 times the normal amount of TP to make sure it doesn't leak through, that's not saving anything.
I've always found that if I need to work really hard to get toilet paper, I'll find a really effective way to get enough and then usually it's even more than I need - but who's going to use leftover toilet paper? On that note, then I start getting concerned with the amount of TP being used. If I use too much, the toilet could get clogged and then I have a whole other issue.
5) WHAT IF THE TOILET GETS CLOGGED?!
This has happened to me about three times. Either it was clogged before and I didn't notice, or I used too much TP, or it was just a cheap toilet. Regardless of what happened, it means that if someone is out there waiting to use the bathroom I'm going to either have to sprint out, or admit to what I've done. There is sometimes the off chance that the timing is just right so I can pretend that I stumbled across it that way. Fear like this is why I'll sometimes flush halfway through and then again when I'm done.
Despite all of this, my need to go trumps my desire for comfort.
That's why I think it's silly for people to refuse to use public toilets.