It isn't all equal.  While it is largely built into the pricing structure, one can have a cash discount at certain gas stations.  Especially for truck drivers that purchase a lot of diesel at a time.
	
	
		
			
				
			
			
				
				Credit card processing fees typically cost 1.5% to 3.5% of the transaction total. Here are some ways that merchants can offset card fees.
				
					
						
							 
						
					
					www.nerdwallet.com
				
 
			 
		 
	 
On average, American Express charges about 1% more than other cards.
The cost is very real.  Consider a small business that does $10K worth of purchases a day.  At 3%, that is $300, or equivalent to the wages of one employee.
So, you get $1K back.  The company building the barn likely lost somewhere around $3K in credit card fees.
A cashiers check is generally free, and a wire transaction is about $30 or so.