It depends, often this is considered an entry level job into the realm of security. In fact, some venues even make this a volunteer position and people eagerly volunteer, because they get to attend the concerts for free. In the United States, each individual state controls licensing of this kind. Some states have little to no requirements for individual security officers, while others require minimum training or certification. Insurance companies may also influence this through policy requirements, in order for a company to insure and/or bond their employee they may have to meet certain training requirements.
Another aspect is at large venues there will be mix of public safety personnel; unarmed and possibly armed security, Paramedics/EMT’s, etc. Different people addressing different aspects of safety and security; like crowd control, cash protection, VIP/executive protection, traffic control, etc.