All budget airlines understandably have their ways to cut costs, but this one has gone beyond all human necessity, let alone human decency, and venture into the fraudulent acts of blackmailing passengers when they arrive at the airport and scamming them out of the money even after they’ve boarded.
You would start noticing the unusual practice of demanding additional payment for normal online checkin - extra money if you would like to check in even for a standard seat - so really their air ticket price, which you have paid in full, does not include a seat - you are supposed to be standing in the plane if you don’t pay extra.
Then you find out that they have shrank the hand luggage to a pitiful 40*25*20 - but even if you comply with this requirement, at the airport they will suddenly bring out a tiny metal scale (which appears much smaller than the already pitiful measurement), and insists that your hand luggage will only be allowed if you can fit it in that tiny scale. If you ask them for a ruler to prove the scale, they will definitely refuse, likely because they are trained to know what to do (and what not to provide, such as the ruler) to scam people out of more money. You will then have to pay an astronomical amount of additional money to be allow to take your pitiful and already compliant tiny luggage.
Then they tell you that not only they do not provide food during the four hour flight, they do not provide water either. And they actively stops you from bringing your own water onboard. Why? You must have guessed - they want to sell you water onboard at an obscene premium. Overall, they don’t want to treat you as a human being, but with utter despise.
And the funny thing is - having paid so much extra, you already part with more money than you would have if you bought a business class ticket at a decent airline. Only that you get to be treated like dirt with HK Airlines.