Interestingly, I was able to reserve an intercontinental flight on CZ on their official website and pay with my foreign bank card (Mastercard) without problems, a first. Last year, it errored out on the payment page and I ended up forced to use a third-party to reserve the flight.

I looked up the same flight on trip.com, and it was 25 EUR more expensive.

For sure, your results may vary with other carriers, and perhaps domestic flights are a different story. But maybe still worth a glance to see if direct résa is more efficient and cheaper than through trip.com