If you click on the link in the following article, you will see a list of check printers who meet certain security standards of
Check Payment Systems Association.
Read more:
http://www.bankrate.com/finance/checking/cheap-checks-vulnerable-to-fraud.aspx#ixzz4V19RCs6T
Harland Clarke, which prints Costco checks is on the list of printers who meet the standard. Don't know who prints
WalMart checks, but one of the other vendors mentioned in this thread is not on the list.
Indeed, the afore-linked article uses Costco checks to show examples of good check printing practices....