I strongly suspect that I am not alone in the stubbornness of my toothpaste preference. I will grudgingly use a different shampoo if I have to as most shampoos don't have too strong of a smell. In any given day I use probably 3 to 6 different soaps, with only the one in my house being my preference (mmmmmmmm coconut ginger) so using some random soap at a hotel is no big deal. But I will be buried deep in the ground before I subject myself to using anything but my usual toothpaste.
It took me years to find a flavor of mint that I honestly enjoy using. Nothing else has ever felt quite right; it even has the right texture! Using another flavor for even one brushing would make me want to gag. Taste, in both senses of the word, is a very personal thing I suppose.
I have never met someone as picky as you say you are with your toothpaste. I don't think you're the norm in any way.
I currently live that proper state of delusion that allows full placebo effect and toothpaste is not expensive enough to warrant a reality check.
Thankfully, that's not a taste related thing like parent, so I borrow toothpaste from friend, family or hotel the few times I travel. Also, since it is feature based, other brands have started introducing similar feature, allowing me a bit of variation.
But really I can understand parent, I have had a period were I was so scared of going to the dentist (I was 30+ at the time) that I was following a very strict routine religiously. I took my toothpaste, brush, rince and floss on my wedding night. They travelled with me to another continent on my honey moon. I took them to the hospital to use on the night my son was born.
But similar to the previous poster, I (and the people similar to myself) don't have this at all with soap or shampoo.
But soap is soap is soap, and toothpaste is the same ingredients in the same concentration for basically every manufacturer (and even then, it's mostly the mechanical action of brushing that gets your teeth clean, not the toothpaste itself -- you can brush with water in a pinch and still be fine). I convinced my husband to buy generic toothpaste and it's saved us DOLLARS (Woo! Big money!) a year!
The only exception I make is for anti-perspirant (also something I haven't ever seen in hotels) because some brands make my skin become red and fall of and some don't work well enough.
So every six months I stock-up on a cocktail of various toothpastes and just use whatever comes out of the bag next.
The only one that was jarring was Corsodyl, and it even had a little chart on the reverse showing that people needed three months ot so to adapt to its taste. I persevered with it because it was free but wouldn't choose it voluntarily.
This is notable in that the one hotel that carried toothpaste felt they had to say which brand. (They were right, I once stayed at a hotel with generic foreign toiletries and only the toothpaste triggered ill ease: wondering whether potentially tainted toothpaste or skipping toothpaste was the higher risk.) But they had also chosen the wrong brand if they have foreign patrons as aquafresh has very little presence abroad.