Getting the first customer or getting a potential customer to give your product or service a chance, getting that first order as it is often called, is challenging not just for start-ups.
One strategy is offering a free service first. For examples, if you have been in central London recently, you will have noticed the Riksha drivers offering directions for free.
When tourists take them up on the offer, they can prove their competence of how well they know the city. I also assume that quite often, they will argue it’s actually faster and possibly cheaper if they just drive them there than going by public transport, earning a first order this way.