The first culprit of this is businesses, whether it's a double room that costs the same if you’re two people booking vs a single person, or a gym membership that offers a discounted couples rate. You can see this incentive everywhere: your phone company, a local restaurant, the theme park. Every company is trying to make a certain amount off you and they usually benefit from larger households. And if you’re shopping solo, they’ll be sure to penalise you for the lack of a second customer.
The next suspect has to be fixed unavoidable costs. When paying bills, the cost for a single person is estimated to be around 80-90% when compared to a household of two or more. This gets even worse for memberships such as Netflix, where, you pay the same no matter the number of people. Similarly, buying home items like furniture and appliances is a much more significant burden when falling on one person. What's worse, the way everything is grouped forces you to buy too much for just you. We’ve all had that head of lettuce go bad on us because we couldn’t finish it in time.
The issue goes deeper. The systems in place make it even worse for single people. If you're alone you get only a stingy 25% discount on council tax or a TV licence for £159 that is charged per household; even the government likes to remind you of your singleness. Adding insult to injury are schemes like the marriage allowance, which reduces a couple’s council taxes by up to £1,000 a year.
All of these in the UK result in an annual 'singles tax' between £4,414 and £18,647. These figures don’t even account for lifestyle-related costs, which increase them to something more like £6,815 and £21,215 respectively. I’m no expert on fiscal policy, but that seems like a hell of a tax just for not having a partner.