Let me help you make sense of this.
Most all tanned cowhides that are done in America come from steers - A Boy Cow that has had his"Nads cut off" this helps speed growth and makes for an easier animal to control. Mama cows as well as bulls do not go to slaughter houses, these animals make the rancher money every time a calf is born, when their use is up they are so old that most don't make it to the slaughter house because the meat is not in demand.
Latigo, English bridle, Chrome tanned, Veg tanned, drum dyed, brain tanned, Etc. are all nothing more than a tanning process in which oils or waxes are added or the tanning formula is changed.
Grades of leather
#1 = tight grain few if any marks or scars
#2 = tight grain a few marks or scares maybe a brand
#3 = utility leather fair grain some marks and scares as well as other imperfections ie: insect bites, stretch marks and fat rolls.
I misspoke earlier about the strops being #3 as I was typing on my smart phone. The strops I will have for the stropping area are #2 grade on the higher side of the belly, (but still the belly all the same). it is not of the quality I use nor do I suspect Neil or any respectable maker would put his name behind in strops. But I am stuck with a belly when I buy a side, I do use them where I can as not to throw profit away. I also use this area of the cow for liners in projects that will not be seen like the inside of a holster. small bags etc.
The easy way to explain it is, like lumber there are top grades and lower grades. the higher up the cows side the better the leather thus it cost more. Go take a good look in the mirror and see what you think is tougher - your belly skin or what is on your back. Cows like people are the same, soft belly firm backs.
The country the animal comes from also plays an important part in quality. A cow that has plenty of good grass, clean water and checked by a vet is a healthier cow and will have a better hide than one lets say from Mexico that was in the desert eating scrub brush and had little water. All my leather comes from 1 of 2 tannery's in the US, Herrman Oak or Wicket and Craig. they both use only American hides. If I buy hides from outside the US. I buy from Argentina or Uruguay. This is because they have good grass and clean water. Horse hides I get from Belgium or France as horse meat is not looked at the same there as it is here.
This is a very brief and simple explanation of leather. bottom line is - Strops are best cut from the back or across the shoulders of the animal never the belly. Using a belly for a strop is like using a pair of old used underwear to wash a Ferrari
Hope this helps