Hmm… this might challenge some of your beliefs here… so caution is to be exercised in reading on…
My current style is tang soo do. I like it. In class we are constantly taught the difference between competition rules/moves and 'real fight' moves and rules. I think that's very important in martial arts. It would be irresponsible of an instructor to teach only the formal side and let students (especially the younger ones who are lucky enough to have never experienced a real fight) believe that they can fight when in fact all they can do is score points in the ring.
Okay… a few things to begin with. Firstly, you're taught the difference… do you mean that it gets explained to you, or do you specifically train different responses based on the context? If the former, it's not really much more than lip service, frankly… if the latter, then good.
But, more importantly, how is it irresponsible for an instructor to only teach the "formal side" (i.e., the actual martial art itself…

. There's no rule that any martial art needs to necessarily be anything more than what it is… if that's a sporting system, then that's what it is… if it's a classical system, then that's what it is… if it's a self defence system, then that's what it is… and, if it aims to be more than one of those things, then that's the approach… but there's nothing "irresponsible" about teaching an art to be what it is, unless it's being claimed to be something it's not. Case in point… I train in Kyudo, as well as Iaido… neither of which are anything to do with self defence… there's no irresponsibility in my teachers in not addressing "real fight moves" (we'll get to that in a bit)… in fact, it'd be a bit irresponsible to claim that they had any reason to address such things.
The point is that there's a lot more to many, many martial arts than just sport, of self defence, or anything else.
A colleague at work bangs on about krav maga being the only style worth learning (he has no background in any martial art as far as I can tell). I like the lad, and he makes a lot of sense a lot of the time, so I did a bit of research in to krav maga. There's no shortage of it on youtube. I've watched many videos, and I just keep seeing moves that we are taught in tang soo do. I don't just mean similarities, I mean the exact same moves in many cases, and minor variants in the rest.
Okay, first things first… if the guy doesn't know anything about martial arts, then he doesn't know anything about martial arts… he might be a nice kid, but he's currently telling you about surgical complications and technique based on watching old re-runs of Quincy MD… that said, let's get to the real issue here.
Focusing on techniques is really completely besides the point.
Look, I get that you're fairly new to this area… and it's a common thing for people new to martial arts to think that the techniques are the important aspect… they're not. The real distinction between martial arts is rarely the techniques… it's in the training approach, and the tactical application of such techniques. For example, look at the forms you have in Tang Soo Do… then try to find them in Krav Maga. Sure, the individual techniques (front kick, rear punch etc) will be there, or a close approximation, but the training method and tactical usage of the techniques will be quite different.
In other words, it really doesn't matter if you see similar, or even the same techniques. That's really completely irrelevant.
So that gets me to thinking. If I understand correctly, krav maga is a relatively new style created by the Israeli military if I'm not mistaken. I wonder if they have taken much of their inspiration from tang soo do. In my intro lessons at TSD I do recall mention that the art was derived through careful study of what can be done as opposed to looking at what instinctively is done, ie there is science to the art.
Er… you might want to question what you were told about TSD, then…
Tang Soo Do is actually younger than Krav Maga. Bluntly, it's based on Chinese systems and Shotokan karate… hell, "Tang Soo Do" is the Korean pronunciation of "Karate" (the original term, referring to "Chinese Hand" - 唐手道

. There is a bit of a claim of older Korean systems, but nothing that is particularly credible. Of course, none of this changes the value of Tang Soo Do itself… or the value of the classes for you… but honestly, you're seeing links where they don't exist.
If my understanding is correct, you are right in the sense that the label 'tang soo do' has only been around since the late 1940s (after Japanese occupation of Korea ended), but the style is based on a combination of what was taught locally at that time, and what is shown in historical record (artwork mainly) dating back much further.
That's the claim… but no, not really.
At our school, they occasionally refer to the style as karate to 'outsiders', but having done both karate and kung fu as a youth, I see a lot more in common with kung fu than karate, and besides karate means 'the way of the empty hand' whereas in tang soo do we have a lot of weapons training, albeit reserved for the higher ranks in normal syllabus time.
Again, Tang Soo Do is the same wording as "karate"… so it's hardly surprising that your system would be referred to as such… and the usage of weapons isn't as much of a factor as you might think with karate…