It doesn't seem unusual these days to hear 'vegans say they're an oppressed group but they aren't' repeated as part of some anti-vegan mantra. Maybe it's just that the vegans I hang out with these days are sensible types, but I haven't *actually* heard that many vegans pleading oppression - but then I suspect that the critics either know whiner vegans than I do, or have more overactive imaginations on the subject, or maybe both. I can accept that whiny vegans exist. Anyone can be vegan, anyone can be whiny, accepting that there can be some crossover doesn't mean admitting to any causal element or even a widespread correlation. I can also imagine that some people's attitudes might induce whininess in any vegans in the surrounding area!
Let's get one thing clear, I don't see vegans in general as an oppressed group. This is not to deny that many vegans are on the receiving end of oppressive behaviour at an individual level - intolerance, food sabotage, even physical threat and assault, connected to their veganism, I've been there a number of times. Of course the stakes are raised if you're also an activist. However, not being able to get a decent choice of food when eating out is not being oppressed. Your colleague or roommate forgetting you don't take milk in your coffee isn't oppression, unless s/he persistently puts milk in there on purpose - and you have the option of not accepting that person's offer of a drink if that's the case! Being followed around by the police outside of a protest situation, getting your emails read and your phone tapped *is* oppressive - but a risk you take when getting involved in certain types of activism. (getting that response for merely being a vegan would certainly be oppression, but it is also highly unlikely - although some in the government might like it to happen, I doubt they could afford to put it into practice!)
On the other hand, I don't think vegans in general *are* more focussed on their own 'oppression' (in the form of not having enough choice in a cafe, people forgetting they take their coffee black, etc) than on that of the animals.
However, there is a 'third' hand there, because vegans are just so damn badass that we can grow extra limbs when necessary.* ;) And on that hand, vegans tend to want there to be more vegans - from an animal rights perspective, that has to be a good thing. One way to ensure that more people become vegan is to make veganism easier to do, and lobbying for more and better choices of food - especially in work and college canteens, but also in resturants and cafes - is one way to do that. As a fairly seasoned vegan, if I go in a cafe and can't eat anything I will be put off that cafe. A newer and less sure vegan might be put off veganism.
There's nothing wrong, then, with making an issue of the lack of vegan choices in a cafe. It's best to do this in a polite, friendly way, especially if the people concerned seem interested. (sometimes there's no point and all you can do is drink your black coffee, eat your apple and plain crisps and write it off to experience) Offering recipes is good, especially if we're talking cake. (Veggies have a selection of vegan recipes, including cakes, designed for mass catering.) On the other hand, acting like a whiny martyr suffering for a cause** is likely to put people off veganism before they investigate the wider world. At least find existing vegan friends to complain to rather than the newbie you're supposed to be helping to make the change! If you genuinely feel like that, you may be an ex-vegan in the making, which is *not* a good way to be for you or for the animals - get some new recipes and a bit of perspective before you put yourself off...
*I wish I had this ability, it would make straining a large pan of pasta or stirring multiple curries so much easier...
**I've probably done my fair share of this, the excuse being that I was a teenager the first time I went vegan and didn't know better. Now is probably a good time to apologise to anyone who was on the receiving end!