Operators reach working proficiency in days. TIG takes months.
That difference is the main reason shops buy the technology. It separates welding capacity from the supply of certified welders, so you can add output without competing for a labour pool that is not growing.
Results are also more consistent between operators, because much less of the outcome depends on hand technique. That tends to matter most on repeat production work, where variation between welders shows up as variation in the finished product.