Does FAR 19.1307 (HUBZone price evaluation preference) apply to task orders / delivery orders competed under a GSA Federal Supply Schedule?

It appears not, since the list of contract clauses for an FSS contract omit FAR clause 52.219-4. So if this is the case, my follow-on question is that while it is clear why the price preference doesn't apply to the award of the FSS contract itself, what is the reason that FSSes are exempt from having to apply 19.1307 for task/delivery order competed under them?

Did you look at Exclusions?

1 9.1304 – Exclusions.

This subpart does not apply to –

(a) Requirements that can be satisfied through award to—

(1) Federal Prison Industries, Inc. (see Subpart 8.6); or

(2) AbilityOne participating non-profit agencies for the blind or severely disabled (see Subpart 8.7);

( b ) Orders under indefinite-delivery contracts (see Subpart 16.5). (But see 16.505( b )(2)(i)(F) for discretionary set-asides of orders);

( c ) Orders against Federal Supply Schedules (see Subpart 8.4). (But see 8.405-5 for discretionary set-asides of orders);

(d) Requirements currently being performed by an 8( a ) participant or requirements SBA has accepted for performance under the authority of the 8( a ) Program, unless SBA has consented to release the requirements from the 8( a ) Program;

(e) Requirements that do not exceed the micro-purchase threshold; or

(f) Requirements for commissary or exchange resale items.