You're missing the point and the legal nuance.
You're right that not every individual provision is framed with “must”, but that doesn’t mean employers have free rein to ignore breastfeeding needs.
What employers must do under health & safety law:
Under the Management of Health and Safety at Work Regulations 1999, if an employee notifies their employer in writing that they are breastfeeding, the employer must:
Conduct a specific risk assessment
Take steps to remove or reduce those risks
Failure to do so is a breach of legal duty and that’s where the need for breaks to express comes in. If the risk assessment identifies that not expressing could cause engorgement, blocked ducts, or mastitis, and the employer refuses breaks, they’re in breach of the law even if the word "break" isn’t used in isolation.
Plus, case law backs this up:
In McFarlane v easyJet (2016), an employer refusing adjustments to allow breaks for expressing was found to have committed indirect sex discrimination.
Tribunals do consider lack of breaks or lack of privacy and dignity as legally actionable.
So while “should” appears in guidance like ACAS or HSE in isolation, the employer's obligation to act on identified health risks is legally binding. If expressing is medically necessary, breaks become part of that legal duty.
This isn’t about splitting hairs over modal verbs. It’s about understanding how the law actually works in practice, and yes, in practice, employers must accommodate breastfeeding needs.