A bit late to the "party", but here is my 2 cents.
I thoroughly research any provider I am going to see. My research includes following them on social media long enough to get a feel for their character, checking out their website thoroughly, and reading reviews. This eliminates nearly all the risk from my bookings and I'd say that 90% of my bookings are very successful. Literally the only risk I face in a booking is whether the provider will click with me and whether the experience will meet my expectations. As you can see from my reviews, the results of most of my bookings are outstanding.
For this reason I have no problem paying deposits, and completing any reasonable screening requests. I completely understand and appreciate the risks taken by providers and their desire to take the steps they think are necessary to reduce those risks by screening.
I am happy to provide my LinkedIn profile, social media links, references from other providers, phone conversations (a new screening method for me), and deposits (some providers take deposits as a form of screening).
Unfortunately I am not willing to provide copies of my ID. It is not because I think the provider will blackmail me, try to engage in identity theft, or sell my ID to someone who may engage in identity theft. It's simply because I have no idea how secure the provider's storage systems are. Is she saving my ID in a folder on the cloud, or on her phone? Is she aware of the security risks of saving any critical information on the cloud or on her phone?
How many apps does the provider (or anyone for that matter), have on their phone, and are they aware that many of these apps are mining/aggregating personal data, and many of them have back doors written by the outsourced contractors who are writing the apps?
I am very hesitant to provide my ID or information to literally anyone unless I am sure they are secure. As an example, I was recently contacted by my credit card company as a follow-up to a survey I had completed on one of their support staff. I was happy to answer any questions related to the support call, but when they asked me to confirm my DOB, address, and email I declined.
Now coming back to providers requiring ID as part of their screening process, I will respectfully decline (without getting into an argument about why), and offer alternative screening methods that she is agreeable with. If we can't reach an agreement on an acceptable screening method then I am willing to accept that the booking will not take place. This has never happened to me so far, but it's always a possibility.