Why do legit companies use short numbers to text things such as promotions?

I get text messages from short numbers such as 611-611. Why are legitimate companies using numbers that seem like scams to advertise gifts or promotions? I would not click on anything in that text without researching it first. The time it takes to research is not worth the promotion offered. Does anyone else have the same suspicions? I have already had my bank account hacked. I am extra careful to a fault. I hate having to check everything I do on my iPhone. This is not normal. Worrying is not normal, being suspicious is not normal, worrying about scammers, thieves, hackers etc. is not normal. Any advice would help. Thanks in advance.