But society can take a 2nd look at laws and change them when they are considered to be unfair. PERIOD (to borrow your style). That's what the original post is asking for. Many laws are deemed unfair over time and as a result they get changed.
I agree that it's patently unfair to consider a 50 year old with a 15 year old and a 17 year old with a 15 year old as the exact same thing. The 50 year old isn't likely to be a junior in the same high school where the 15 year old is a freshman. He or she is more likely to be a teacher.
Teacher and freshman oral sex = very, very wrong.
Junior and freshman oral sex = is that the same thing?
Because come on - how can you claim to be protecting the "innocence" of a 15 year old when he or she is naturally ready to start exploring their sexuality?