I saw the pics of your straightened hair, and at least in the pic, it didn't look poofy or fried! It looked good - it just had the odd flyaway and bump which if you brushed it down and wrapped it could probably be fixed.
I'm multiracial and my hair is 3b/3cish and doesn't look that good when I do it myself - if I try to straighten my own hair, it never goes really straight. But my stylist can make it amazingly silky and straight. It still has a lot of volume because that's just my hair, but it is straight. Which makes me think that technique/the amount of tension you are able to put on the hair is the main factor in straightening, not hair type.
In terms of chemical straightening, my hair was always resistant to that too. My stylist used to say that my type of curl was much harder to straighten than most heads of tighter curls (4a and 4b) so I think that the type of hair you and I have is very resistant.
My hair is coarse, but I don't think all 3b/c's are. Some have fine hair, some silky, some cottony, some a blend.... it all depends. Same with 3as or any other hair type.
I also think hair thickness is a factor in straightening. I have insanely thick hair - like we're talking a 9 or 10 inch ponytail base! as well as quite a bit of length - so that makes it much harder than a 3 or 4 inch ponytail would be. The more hair you have the more patience you need and your hair is going to start airdrying so you have to keep wetting it... it's much easier with a stylist's help. My stylist sometimes takes 3 or 4 hours to press my hair straight, but it will last forever. I also cannot get nice looking straight hair with a flat iron - it HAS to be a hot comb that can get right to the roots, and I have to wrap it all the time when I am home or in bed.
In terms of race, I think not only texture, but also curl pattern, can tend to differ between different ethnicities. I notice that a white person with 3b or 3b/c hair tends to have a different curl pattern than a Black/mixed person with the same curl size (not always, but often.) Very tightly curled Black hair, like 4a or 4b, has a flat, ribbon-like cuticle while less curly Caucasian hair has an oval cuticle and straighter hair has a round cuticle (I think that's correct - anyway, the cuticle shape is different.) So I think those of us who have partial African ancestry and partial "other" ancestry have a partially flat cuticle but not AS flat, where those of European descent with curly hair tend to have a round cuticle. Because I notice that "our" curls tend to have a different shape and pattern - they are often more of a "coil" and less of a "spiral" if that makes sense. Or we will have the very S-shaped curls. I would describe "our" curls as corkscrews and many white peoples' curls as ringlets. I think our curls also tend to be more defined and clumped and distinguishable from each other even though they are very small curls and a lot of white peoples' hair tends to stick together more naturally, if that makes sense. Like, Nicole Kidman and Keri Russell's natural hair has a different look and quality than Tracee Ellis Ross or Rachel True's natural hair.
Of course, with all the race mixing and crossing over the years, and all the things we do to our hair, you never really know what peoples' backgrounds are and there is nothing really definitive when it comes to hair and who has what type. There are genetic tendencies but I think looking at hair as "Black" or "white" doesn't really make a whole lot of sense with all the diversity we have as people.
Tgreyz, I think if you found a really good stylist to straighten your hair you would be amazed at how nice it could look.