Wow.
Surely it should be 16 for both.
It's 18 for women, 21 for men.
Problem is maturity, kids are raised wrapped in cotton balls in subcontinent, a 20 something is called a boy/kid (a bacha) and 30-40 is considered youth (see people who occupy memberships of youth wing of various political parties, someone of them are in their 50s lol.)
In such a scenario, ammi/mummy's beloved son gets away with anything. Even ruining the life of newly wed wife. Wife would be called names and husband would be seen as ideal son who loves his parents so much. Newly wed women become financially reliant on in-laws and take abuse as they know their husband is not mentally mature to be a good patient listener, not financially independent yet. and dare say he is not a good lover, she will be called chagal or badchalan.
So in my opinion, if it's an arranged marriage age should be way higher. These people are not mature yet. It's a ticking time bomb for unhappy marriage, dead bedroom, decades of abuse.
Some people see bahu as nothing more than a bhed-bhakri (goat-sheep). Marry her, she is your property now, keep asking mummy for what to buy or what to cook in dinner.