I always offered paper pants for years, then one day we ran out That was when I discovered how few clients actually want them.
History lesson...
When Brazilians first became a thing the wax wasn't ideal for the job, and therapists had to be very careful not to get wax where it wasn't wanted. For safety therapists worked with knickers on - pulling pants to the side. It helped with stretching the skin and the client felt more covered - (plus a lot of therapists were weirded out by such an intimate treatment. Many of us couldn't understand this waxing fashion, it was great that "pants on" was protocol and we could truthfully say that we needed pants on for health and safety and improved comfort). Some pants had very little give - or were control pants and not designed to be stretched in different directions - so paper pants were always offered as an alternative. Clients were brusquely told to put pants on if they arrived knickerless in leggings.
When the next generation of waxes allowed us to drip straight up the middle, old fashioned therapists like me had acclimatised to skin treatments, however clients were very attached to their pants and reluctant to shed them. I offered paper pants because I was used to offering pants and many of my clients wore them - so I thought it made them more comfortable.
In recent years I've seen young clients arrive and be quite started to be offered pants and to ask how on earth we are going to do a good job with pants on - some have been offended by the idea that we might not be comfortable with full nudity. So I explained that it's a generational thing - long term waxers are used to knickers and newbies didn't bother, clients get to choose.
When I ran out of pants I realised that I was wasting my money and making life difficult for myself. The last 10 pairs of pants lasted me more than 6 months - in other words, I have one regular client who wears them - no-one else cares!
I still have 480 pairs of pants from my last stock order so if I have a new client who looks anxious I give her pants. I just say that it doesn't make any difference to me, but an anxious client is harder to wax so if she prefers to wear them, feel free.