I guess this difference in NFC may be the reason for the following:
1. iPhone X allows balance transfer from an existing card, while iPhone SE doesn’t.
2. iPhone X simulates a physical transit card and functions on a tap, while iPhone SE only stores card information and still needs your fingerprint before payment, thus causing more inconvenience.
Conclusion: Apple’s philosophy lies in here. You’re bound to upgrade your device annually, or at least every 24 months.