Are spiral stairs less safe for public use than other stairs?
Spiral stairs could be less safe as they aren't perfectly even on both sides. However, they are typically used for architectural design because of space requirements that the client's home or business has.
Cost wise, spiral stairs and railings usually cost significantly more than straight stairs and require far more custom fitting than your standard straight railings.
Curved and sloping railings are helical and are both curved and twisted by nature