"During the 1990s, the introduction of retirement visas and non-immigrant visas for specialised groups bolstered the necessity of visa agencies. They offered relief from lengthy queues and cumbersome paperwork through services such as address verifications and residency certificates."
Silly me I always thought it was for those who didn't have the 800,000 baht and/or medical insurance, depending on the visa. If memory serves me right, I never heard any of my friends say "I'm glad I paid the 19,000 baht for the relief of not standing in line".