I've often wondered how many of the MN's children with a variety of SN issues have been actually diagnosed by a professional, there does seem to be a far greater that average number in the population?
@tillytrotter1 One of the hard things about having a child with a non-visible disability is people who think it's made up or that it's not 'real', your comment perpetuates that stereotype and is not at all helpful. It can be very isolating being a parent of a SN child, I won't go into the details but for many families the best - and only - place to get advice, support, and solidarity is online which is why online communities such as this seem to have a large percentage of parents with SN children. This is especially true is parents whose children are now adults, SN children grow up and what little official support there is vanishes almost overnight once they turn 18 so again online is the best place to go.
Would also like to point out that SN and SEN are not the same thing, while there is some overlap between the two groups you can have Special Needs without having Special Education Needs. DS has SN/a disability but until a few years ago was not on the Special Education Needs register as he had not yet met the needs threshold for inclusion. A few children in his intervention group at school have Special Education Needs but no additional/special needs or disabilities. Some of the children have both.
OP, YANBU. If I didn't know a child and saw what most would class as 'bad' behaviour then I would always err on the benefit of the doubt because it's not pleasant to judge people or for others to feel judged however yes, there are rude, bad mannered children out there. Some have SN, some don't. Some children with SN are polite, some are not. Sometimes their lack of manners is due to their SN, other times it is not. DS can forget his manners, particularly when he's in a heightened emotional state, even with a reminder to say please/thank you or a very pointed "and what do you say, DS.......?" it doesn't always register but in those situations I'd do it on his behalf and then have a talk once he's calmed down.