Design a reservation and payment system for a parking garage.

A robust parking reservation and payment system requires careful consideration of data consistency, availability, and performance. For real-time spot allocation, synchronous replication might seem appealing for immediate consistency. However, it can introduce latency and reduce availability, especially under high load. A more scalable approach often involves asynchronous replication or eventual consistency models, coupled with strategies like optimistic locking or distributed transactions to manage concurrent reservations and payments effectively. The system should also handle payment processing securely, integrate with parking hardware (like gates and sensors), and provide a user-friendly interface for customers to find, reserve, and pay for parking.