Granted Sezzle is competition, in a sense everything is competition. However Sezzle only claim 3,000+ stores, and 250,000 people shopping with Sezzle. By comparison to APT Sezzle is small. Further buy comparisson to APT Sezzle is expensive "Our standard payment processing fee is 6% + 30c per transaction."https://legal.sezzle.com/merchant
I understand ( and I may be wrong) that APT standard fee is 4% = 30c obviously 'standard' fees can be negotiated.
APT have 4.5M shoppers and 36,000 stores? DYOR
Keep in mind that if your running an operation with a 10% net margin, and you can save 2% of gross revenue on fees that is 25% of your net margin. for retailers that are doing it tuff, that may be the difference between survival and closure.
Sezzle.com
https://sezzle.com/how-it-works