They do get slick, I'm speaking from experiance. Got a big ouchy when I slipped and fell onto the back rail edge with my ribs. That was back when I first started and worked by myself. Wish I would of had someone to drive me home.
several years ago when i had first started... i got new ramps... went to load my 36 gravely into the truck... snaaaaaaap! the 500 pound walkbehind when flyting and landed on my toes! never bought wood for ramps and home depot ever again.
I dropped a few walk behinds in my day. My 61" scag makes the loudest bang though. Dont dont do it anymore cause i own a trailer, but every once in a while you load your truck with ramps. Just got be careful.
I've had a close call or two myself since getting my new trailer. Mostly, it comes when I'm stepping off the ramp onto a curb (stepping off the ramp sideways), instead of taking the extra half-second to walk down the ramp proper, with shoe tread and gate 'tread' in proper sync.
On a related note, I took a fall off a retaining wall my first day back from vacation (three weeks ago now?). Cutting a lawn I've cut a couple hundred times at my normal pace. When I went to step as I turned the mower, I felt the sickening rush of adrenaline as my foot caught empty air. I dropped, but bounced right back up, pacing back and forth and saying the obligatory "Oh God, Oh God" as I waited for pain to set in on my knees, back, neck, etc.