All awards seem to be discriminatory. My boy is well behaved but the naughty kids and the special needs kids are often getting stars in jar for doing stuff my boy does all the time.
Do you actually know any children with SEN? Or severe anxiety? Or emotional difficulties? For some children just sitting still in class is a HUGE effort and they deserve to be rewarded for that. And a lot of 'naughty' children might have SEN (diagnosed or not), difficult family situations, attachment disorders, anxiety etc. Behaviour is communication after all. Just be grateful your child is able to behave well rather than feeling that he's being discriminated against for not getting stars.
Re attendance awards, it's because of Ofsted requirements- low attendance equals a poor rating, which lowers the number of people applying to the school, which lowers the school's income. Presumably they don't make a distinction between genuine sickness and holiday/couldn't be bothered/late as people will just lie.
People wanted a choice of schools, and wanted to know which were 'best' so we've ended up with league tables and Ofsted requirements. Then everyone complains about Ofsted and SATs pressures.