Yes. Processing payroll usually requires your employer to go through a whole process where taxes are calculated and withholding amounts are added in for various benefits. It’s a huge hassle to do this “out of cycle” for most companies.

With an advance, they’re just loaning you some money out of your next paycheck. They can just deduct it from your regular pay. Much easier.

Edit: just because it’s easier doesn’t mean they’ll do it. If you stop showing up for work, they’re out the money, so there’s some risk.