The app, regardless of it's legal structure or ownership would have to produce financial statements every year, which include a profit and loss account and a balance sheet. These Statements do not detail individual clients or customers. The financial statements are submitted with Annual Returns to Companies House, Revenue Commissioners, Bankers/lenders, Investors and shareholders. If further details are required by revenue an audit may be conducted which usually takes a snapshot or random extracts unless there is a serious investigation relating to the business and not the clients/customers.
There are data protection laws in place to protect how your details are managed and who has access to that information.
When a driver signs up they can be assigned a number, separate to the necessary vetting procedures drivers go through prior to joining. Figures and stats can be calculated/broken down by reference to a number and not
the drivers personal details. The information would still be there but not readily accessible. if the authorities really want it they will get it and as mentioned by other posters there are easier ways to get it, meters etc.