do you have proof to back up your claim?
if you buy a DVD player from a United States retail store, it's NTSC only. getting one off the internet is different as you can get an all region player that can output both NTSC and PAL.
TV's can only accept one kind of signal (NTSC or PAL), so you will need a signal converter to be able to convert the signal from one video standard to the other
My best friend lives in LA and bought his TV and DVD player there. They play PAL DVDs just fine. Refute your claim (which YOU provided no proof for) much?
Since the early 90s, TVs have pretty much all been manufactured to accept PAL/NTSC/SECAM signals because it's cheaper and more efficient to create less models rather than make region-specific models. It also reduces manufacturing costs. So, basically, you're wrong. I'm not saying you're an idiot or anything, but you shouldn't go around claiming things without checking you're correct first. If you were right, my TV would not be able to accept the signals from my NTSC Xbox 360 and NTSC games, as I live in Australia, and we use PAL here.
About DVD players, you WERE right; back in the early days of DVD, players were PAL only, NTSC only, etc. But these days, it's unlikely that you will find a standard-specific player. With regards to buying one in a store and one on the internet, well that is just plain wrong. Companies don't make different models specifically for store or internet purchases; that's just ridiculous.