Still looking at HR 3590. It is a hefty document after all.
On page 459 of the PDF linked above, we have:
SEC. 4207. REASONABLE BREAK TIME FOR NURSING MOTHERS.
(r)(1) An employer shall provide—
(A) a reasonable break time for an employee to express breast milk for her nursing child for 1 year after the child’s birth each time such employee has need to express the milk; and
(B) a place, other than a bathroom, that is shielded from view and free from intrusion from coworkers and the public, which may be used by an employee to express breast milk.
The bill goes on to say
An employer that employs less than 50 employees shall not be subject to the requirements of this subsection, if such requirements would impose an undue hardship by causing the employer significant difficulty or expense when considered in relation to the size, financial resources, nature, or structure of the employer's business.
Either way you look at it, this provision imposes significant costs on a small business. Either the business has to divert business funds to provide such a facility or it must be prepared to expend the time and effort and legal costs to legally prove that such accommodations will impose an undue hardship.
When the costs of a business increase, they cannot magically create money (as opposed to the way governments seem to think they can) to cover those costs. The higher costs must be passed on (to whatever extent feasible) to the prices of the goods and services such businesses provide. Given that all demand curves everywhere are downward sloping, this means they will be able to sell less. If a business is selling less, it means it is producing less which means the business needs fewer workers. The net effect of these provisions is always to depress employment, just like an explicit tax.
At least, with a tax, a business knows what it must pay. With a provision like this, there is considerable uncertainty as to what type of a facility will be considered acceptable if an employee ever decides to file a complaint.