"DUI isn’t a serious offence in the US, so that’s ok too."

It's definitively very serious, and can be enough to get a visa denied.

I'd like to agree with you, but I once found myself as the only person in a mid-sized firm who didn't have one on my record. It was an eye-opener.

And they all went through hassles and spent a lot of money to resume a normal life.

That's a highly understated way of putting it.

Very serious? Millions of people in the US have one with no serious effects on them whatsoever (I'm talking of DIU and being caught, not hitting someone on it). E.g.:

"The penalties for drunk driving vary among states and jurisdictions. It is not uncommon for the penalties to be different from county to county within any given state depending on the practices of the individual jurisdiction. Some jurisdictions require jail time and larger fines, even on a first offense. For instance, Ohio requires a mandatory 72-hour jail sentence for a first offense conviction; however, the jail time component is satisfied by attendance of the Ohio A.W.A.R.E. Program, which is a 72-hour alcohol-education program. Compared to many other countries, such as Sweden, penalties for drunk driving in the United States are considered less severe unless alcohol is involved in an incident causing injury or death of another, such DUI, DWI or OWI with Great Bodily Injury (GBI) or Vehicular Manslaughter."

"Wisconsin regards first offense drunk driving as a municipal offense, and New Jersey treats all drunk driving cases without serious injury or death as traffic violations."

You're talking about people already in the US (citizens/residents). If you're trying to get a US visa from your country and you have a DUI on your record, it makes it much more difficult to get approved.

FYI, a US citizen with a DUI will likely get denied entry into Canada -- you usually need to be deemed "rehabilitated" or be granted a temporary stay visa before allowed in.

https://help.cbp.gov/app/answers/detail/a_id/402/~/entering-...

You’re being pretty selective there. MANY states require an Ignition Interlock Device:

http://www.ncsl.org/research/transportation/state-ignition-i...

This not only costs thousands of dollars – a very significant amount of money to the vast majority of Americans – but it also SEVERELY limits an individual’s ability to drive a work vehicle.

Yes, prison time is not always involved, but the financial cost of a DUI can be quite serious.

We're talking about people trying to visit/immigrate. The US is a very different country if you're a Citizen or not.

Got my H1B with a wet reckless offense (still a DUI I think). No question asked at the embassy. I even figured out later that I went to the embassy while having a warrant (lawyer never went to court because he died 2 days before).

It doesn’t mean you need to drink and drive or that it will apply to you, I think I just went crazy lucky that day at the embassy.

Yeah it's probably not 100% hit for sure. Some people in my University had questions when renewing their (student) visa because they got a DUI driving a bicycle.

Canada sometimes denies entry to US citizens who have been convicted of DUI. They have a data sharing system in place and can check US criminal records on the spot.

Yep a friend of mine is banned from Canada for that.

If you’ve got the money, there are a couple of good ways around that. This article seemed to explain it pretty well:

https://www.adamgreenmanlaw.com/blog/can-you-go-to-canada-wi...

Iranian nationals are currently barred from travelling to the US, so I imagine a criminal record is not even necessary to get the visa denied.