Ah, but the one you pulled out of your Christmas stocking was likely an "entry-level" instrument or worse. Reeds that are already out of tune, uneven or nil reed response, reeds going flat after a few plays...untunable guitars made of plywood...cheap plastic recorders...those Chinese fiddles that even a seasoned sessionista couldn't scrape a decent tune out of... two-quid squawky tin whistles...

It's how to put children off playing music for life. When our two were learning the clarinet and concert flute respectively, we found the same thing. If you want your kids (a) to sound good, (b) to stick with it and have fun, "entry-level" should be regarded as dirty words. We had to pay relatively big mazumas, or at least do some canny second-hand purchasing, expert in tow (then do some servicing), in order to get properly playable instruments.

Mind you, you can get excellent blues harmonicas for about thirty quid/dollars. Life is such a learning curve.