Also, they didn't fly everywhere. For a while, the WWF guys only flew if the trip was something like more than 300 miles. I'm not sure how it works now. Often, the towns were booked in order of proximity.
Stampede Wrestling had a standard loop they'd run with most of the guys traveling by van. During the harsh winter months, Stu didn't even run shows in certain Canadian towns because the snow made it impossible to get the ring truck and van there.
The AWA had their own piece of shit plane to transport their wrestlers when needed. Most of the boys were terrified to fly on it, especially after Mad Dog Vachon once opened the hatch while they were in the air.
As for today, most of those guys I'm sure have connections within the company.
It used to be a promotion/territory had one ring truck that would transport the ring, steps, guardrails, and crew. Today, WWE is a huge-scale production with stages, lighting, pyro, jumbo-trons, etc. There are so many stage crew workers and trucks that travel by ground, it wouldn't surprise me if guys on some of those trucks are also transporting PED's for the select few who somehow work around the "Wellness Program."