Toilet paper is an essential for both genders.
In the UK tampons and pads have VAT charged on them (as they count as a luxury); there is a campaign to remove this and it has been reduced to 5%, but it's still there (due to EU regulations I believe).
As a side point, in many parts of the world, toilet paper is not an essential; it's regarded as a dirty and unclean western practice.
In contrast, I can spend an order of magnitude less on razor blades, as a pack of Harry's blades end up being something like $2/each, and that's basically about a dollar or two a month (or less).
For menstruation, you can do free bleeding.
For defecation, you can use a bidet, or go old-style with corn cobs. You can use an odd number of stones, as specified by Muhammad.
The same goes for shampoo (don't need it), deodorant (don't need it), and many other things.
What this all boils down to is a fear of having other people think you are weird, defective, dirty, gross, etc.
In walked the bidet.