Yeah upon further research I unfortunately noticed that too. Kinda sneaky.

However, a few times it really produces a "deal". For example, flying with Aegean from ZRH to IST on Sept 13 OW is priced at $75 with $15 in CheapCash compared to $77 if you book the same flight with Aegean directly.

Or, same day, flying OW with SAS from ARN to TXL is priced at $65 with $15 in CheapCash. This is the same price as everywhere else. So $15 cheaper (if you anyway need to book a hotel).

Also a good one: ARN-FCO Nov 14 to 17 with SAS (rt), $128 with $30 in CheapTickets. It's $128 everywhere else as well (including on SAS own website).

I also noticed that OW fares with an overnight layover get $30 instead of $15.

A lot depends on the airline, it seems. No chance to get a good deal with LH/LX for example because of their controversial OTA fees.

Not sure how it is with US airlines.