Which regulations and applying to which sectors?
On the strictest interpretation it isn't everyone and only applies to a few roles.
However just like other compliance it tends to be applied by financial firms in a risk-averse maximal approach rather than a minimal approach. So it's not uncommon for background checks to be applied to all staff at a company or who provide services to such a company.
I don't agree with such maximal interpretation of the compliance rules, but this is how it happens and having that conversation with HR during interviewing is just going to get you excluded.
The original poster likely wants to avoid US travel too... given that it will require a visa due to moral torpitude.
https://www.collinsdictionary.com/dictionary/english/turpitu...
https://en.wikipedia.org/wiki/Moral_turpitude
Turpitude: very immoral behaviour; from Latin turpitūdō (ugliness). Not a word I was familiar with - adding this comment for others.
That they do not consistently enforce at time of entry is luck on your part in that entry instance, but either way they now have the ability to freely deny entry forever due to you not following their rules.
Sucks to be you now, the US system does not believe in rehabilitation and if you've been arrested you need a visa. You are not entitled to use the visa waiver program that exists between the UK and US and allows visa-less movement with only an ESTA.
If you want to visit the US in the future, or your career requires such visits... I suggest applying for a B1/B2 visa, if they think you're no risk they may even grant you a multi-year multi-visit one. If they think you're too risky they'll only grant a single timed visit visa, or you'll be fully declined.