Yes, but they are certainly more proportional that what we have. In the US we have this stupid magic line of 18 where all of a sudden you apparently gain some magical sexual clairvoyance!
And you want to change it to some other magic line of [insert age here] where all of a sudden you gain "magical sexual clairvoyance!"
Ultimately the law has to be practical and consistent. As a society we don't want teachers fucking their adolescent students. We don't want them fucking their students in general, but on the basis of consistency and practicality we draw the line at underage.
Some want to argue that some teenagers are capable of "handling it." Sure. But a great many aren't, and we can't have the situation where people say "I thought s/he was mature enough" as a defense. Additionally, we can't or don't practically want a system where we have to check each kid and stamp them for sexual maturity. While I guess that would help fill out jobs but it's not exactly a great use of resources.
Finally, there are some that want to say that because it's a young male, it should be looked at differently. What you are doing by saying that is perpetuating the idea that males cannot be raped except in extraordinary circumstances. Furthermore, you continue to assert your patriarchal view of women's sexuality by "protecting" them further into life, saying they're not ready until later.
Your first reaction to a 15 yo girl having sex with a 30 year old male teacher is "string him up!"
Your first reaction to a 15 yo boy having sex with a 30 year old female teacher is "'atta boy!"
This reaction betrays a sexist point of view. All this serves to do is reinforce harmful gender stereotypes. As it turns out, a lot of teenage girls want and have sex. A lot of teenage girls are more emotionally and mentally mature than their male counterparts. There are teenage girls that desire and attempt to seduce their male teachers. Just as there are teenage boys that aren't ready for sex, that are uncomfortable by the pressure put on them to be sexually ready and active, and who don't want their first time to be with someone who has authority over them, not to mention emotional, intellectual, and physical dominance over them.
Trying to take away agency from females and placing it all on males is, frankly, bullshit for both genders.
You attempt to obfuscate the issue by making this kind of assertion:
We do this because we (as a society) are too politically correct to acknowledge that having sex with a teenage boy renders no real harm to the boy's body or mind, whereas a teenage girl bears the potential responsibility of bearing a child by her partner.
You go from making a claim about a boy's mental state, and then comparing it to a girl's physical state. This quote does a lot to illuminate the issues with your point. First, you imply that boys are somehow more resilient mentally to this sort of situation, to which I'd like a citation, or at least a definition of "real harm." Right now it smacks of bullshit like "boys have keys, girls have locks" breakdowns.
Secondly, you act as though pregnancy is something that is completely a non-issue to males. What happens if the boy gets his teacher pregnant? Do you really think that males have no emotional attachment to having a potential child? That maybe the boy would want to see that child brought to term? That maybe the woman would bring it to term, despite the boy's potential wishes otherwise? How about that a 15 year old boy is really not an ideal father in our society?
Ultimately it makes sense from a social point of view as well as a justice point of view to draw a clear line. Teachers shouldn't fuck their students. Adults fucking minors is rape.