It's just an order on a computer why would you care?
Ah, well, actually I can answer this.
For example, since this is student finance, it might be construed as a financial account, and if it's allowed to go over-drawn, as a credit account - in which case, plenty of places would only speak to the primary account holder. I bet plenty of people here, including me, thought they had joint accounts on things, only to call up to sort something out and discover that no matter how you'd filled out the form originally, the provider had put their (male) partner as the primary account holder, and they wouldn't let the secondary account holder make changes.
Many women missed out on shares a few years ago when there was that flurry around the building society buy-outs, because they went to the primary holder. DP and I nearly had issues with our letting agent because they decided to address letters to him (despite knowing he was going to be away for 6 weeks, and despite me being filled in as the point of contact on everything). Barclays bank started addressing statements and letters to my partner when I added him to an account I'd had for 20 years (to their partial credit, they fixed that when I kicked up a fuss)
That's why it matters, not just because it's sexist, but also because more often than not, it has real-world consequences.