There is no state license for Limos unless you are talking about Limos that perform Taxi services such as picking up a customer who hails them down.
If the Limo transports a person with a prearranged agreement and prearranged destination(s) this does not fall under the laws for taxis.
There are Gypsy Taxis that pick up customers without prearranged plans and do not have a Taxi license. If some Limo services are doing this that would be illegal.
Someone please correct me if I am wrong but I have researched the laws on this.
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