I would love to fly Thai Airways but their prices always seems to be way more than everyone else. I was looking at a flight from HND to BKK. ANA has their flights for around $600. Thai airways has a codeshare with ANA in which they fly a B747. There price is $2,400. I know this airline has been taking loses. How do they expect to make a profit with these uncompetitive prices?
The "problem" is most likely that you are trying to book on a code-share flight.
Most airlines in the world (very few exceptions) that have code share agreements discourage bookings solely on the point-to-point code-share flight.
The intention is to keep the few blocked seats on a code share flight for connecting passengers.
So, if you want to fly non-stop HND-BKK only and you want to fly on NH you can book a NH-ticket and the prices will be "normal".
As soon as you try to book this route with a TG (code-share) flight number the price will be sky high because TG wants to keep these few seats availlable as code share for passengers flying (e.g.) HND-BKK-FRA.
Still, sometimes fares on a specific route are very high because market conditions allow these airlines to charge a premium for some reason.
So, if TG is asking 2400,-$ for that flight in this particular case it seems they´re likely to be able to fill the seat with that fare which turns into a huge profit for them - but as I said there are several conditions at play.
I just checked random dates on the route and it seems that it in your case most likely their lower seat buckets are simply sold out.
Sorry, I could not list all possible reasons for such high fares but there are quite a few scenarios/reasons why/where such high fares appear.
(e.g. another reason might be a pending flight cancellation which usually gets lower booking classes inventory clocked before the whole booking class inventory gets blocked later)