Nothing like that at all in my post. I’m saying that because a horse is inexpensive, it doesn’t mean it’s less likely to have something career limiting that can be detected on rads. I’m saying price is nothing to do with health.
Nowhere at all in my post did I define what rads, ultrasounds or other imaging people should or shouldn’t do on a PPE. Zip on back up there and read the post again. 
Me either - that’s a pretty unusual circumstance so it doesn’t make sense for me!
See again, my point is that keeping an unsound horse alive costs about the same as keeping a sound one. Except you can’t ride it.
Let me lay it out: two scenarios.
Horse 1, age 6. Horse lives to be 20. 14 years of ownership. Horse is sound and in work until age 17 - 11 years.
Purchase price $10,000
Cost of PPE $5,000.
Board and feed per month: $800. Vet, shoeing, etc $200. Annual cost let’s call it $12,000
Total outlay on board for 14 years without any mention of inflation, just to simplify things: $168,000
Total cost - purchase, PPE and board: $183,000
Amortized cost per year of useful life: $16,636
Horse 2, age 6. Horse lives to be 20. 14 years of ownership. Horse had kissing spines brewing on purchase, but no PPE done so not caught. 1 year after purchase horse becomes symptomatic and starts bucking violently. Surgery is performed, unsuccessfully, at a cost of $5,000
Purchase price $10,000
Cost of PPE $0 - no PPE done
Board and feed per month: $800. Vet, shoeing, etc $200. Annual cost let’s call it $12,000
Total outlay on board for 14 years without any mention of inflation, just to simplify things: $168,000
Total cost - purchase, surgery and board: $183,000
Amortized per year of useful life: $183,000
Obviously things don’t always happen quite this simplistically, but also obviously an unsound horse, (whose issues could have been seen on rads etc) cannot be sold or used. Unless you’re a person with a great job/unlimited funds, you’re stuck with that horse, and likely cannot afford another horse to ride until #1 dies. BTDT.
Now, if you have lots of $ or land, throw it in a pasture and go buy another horse. This thread is not for you.
And if you just like having a horse around and don’t care about riding: magical. Skip the PPE and enjoy the pony.
But as you can see from the above, even a cheap horse costs a LOT more than a PPE to keep.
PPEs are not a luxury for the rich, they’re (relatively) cheap insurance for those of lower means.