No, I didn't check them out. I
assumed they're transormerless, which is a bad thing to do.
You're probably right. Most of them have enough room for a small high frequency isolating transformer. But some of them are so small, they don't seem to have enough space even for a capacitor.
After something breaks, I usually open it up to see how it works. So, I have pretty good idea how cofeemakers and toasters are built. But none of these little power supplies broke on me yet