Ours are pig scales, heavy things too (Got 2 wheels and handles to pull, don't push, it'll kill you).
Weaners when we had them, Shetland sheep no problem, mules got in, as have my Wiltshire horns (very carefully due to the bars above their heads!) As long as they can see the end gate, they have no issue walking out (As long as i can get them in!)
Which was an issue with some of my Dorset Downs! Not all, just some, you know the kind, the ones who will plonk their front feet right at the entrance to the scale, but not quite On it and no amount of pushing, swearing, threatening with death....... Or bribing with food (someone standing with a bucket at the other end) will get them to pick their feet up and "walk on". So either you keep going, or know that b*tch has beat you this time! There's also the ones who you know WILL fit in the scales and the minute her feet are On the scales, she decides to breathe out and suddenly gets stuck in the entrance gate, so pushing with hands, shoulders, even holding onto the scales and pushing with your foot, nothing working, she's stuck, then the bucket is shook, and all of a sudden, fat ewe becomes slender again! (Her name was Fiver and one of the best Dorsets I ever had, guessed her weight after that!)
I'm assuming modern sheep scales are more forgiving for different sheep styles as are modern pig scales!