The Export-Import Bank turns a profit. How is something welfare if it actually makes money?
Because it's a subsidy in the sense that the big corporations get lower interest rates, then they would from a private lender. It only makes money if one ignores the time value of money, to wit that the Feds could earn interest on the money other loaned. And in an omega, economic collapse situation, that hits every 10-20 years or so, the scheme could lose a lot of money. Shorter term profits are not a good indicator of the long term financial return of this sort of program.
The corporations aren't getting the loans. Foreigners are getting loans to buy goods from the United States. Every other country does this.