I have never been in a CL, but I did travel with senior politicians in the UK. Airport lounges are an excellent space for networking and having conversations between people who would never seek out time for a formal meeting. This included conversations between political opponents. These informal conversations can be immeasurably useful in making the system work. It would be an epic own goal to take away the opportunity for these kind of chance encounters.
Plus, I never saw any of these politicians particularly revelling in the supposed luxury. At most they would pour one drink, most of which would be left in the glass when the plane was ready for boarding.