open stairs

Bullseye!

You're right in a sense. In the likes of the UK and other countries, there are Building Control Inspectors or similar who work for the Local Authorities and will carry out inspections for compliance with various regulations.

Regardless though, the ultimate responsibility for compliance lies with the designers (to design in accordance with the regulations), the installers (to install in accordance with the regulations), and the certifiers (to certify that the work was carried out in accordance with the regulations). People doing those jobs wrong leads to breaches of the regulations. The regulations or lack of independent inspectors doesn't negate those professionals' responsibilities.

Regarding your stairs, if you want open risers, you need to ensure there is no gap between stair threads larger than 100mm. You could install a small upstand at the back of each step which would make the risers semi-open but reduce the gap to less than 100mm, or fit a bar across the middle of the open risers, or rather than open risers use a suitable translucent material as the riser which will allow light through but still be of sufficient strength to act as a stair riser.

Either way, compliance with the regulations is a requirement.

Sections 1.1.7 & 1.1.8

Would a spiral stairs work, they look the business and take up less space than a standard one - the downside is that's it's a pain trying to get furniture up to first floor