Can You Explain This Use Of Tax Stamps?

Found this package tag with tax stamps on it with a registered mail cancel. Valuable Insured Mail was handled same as registered mail with its chain of custody documented under special conditions mostly involving money, coins, and negotiable paper. This appears to be a personal package? Information needed on if there might be a valid need for there use or possibly invalid use for postage and fees, or???

Previously discussed here

https://goscf.com/t/64222&SearchTerms=parcel,tags

Here is yours

https://goscf.com/t/63444&SearchTerms=parcel,tags

Nice tag, these usages are not all that common, relatively few were saved.

Per Google Books:

REGULATIONS 55 RELATING TO STAMP TAXES ON DOCUMENTS
(EXCEPT ON ISSUE, SALES AND TRANSFERS OF CERTIFICATES OF STOCK AND SALES OF PRODUCTS FOR FUTURE DELIVERY)
IMPOSED BY TITLE XI OF THE REVENUE ACT OF 1918
(APPROVED, FEBRUARY 24 1919)

PARCEL-POST PACKAGES.
SCHEDULE A 14. Parcel-post packages: Upon every parcel or package transported from one point in the United States to another by parcel post on which the postage amounts to 25 cents or more, a tax of 1 cent for each 25 cents or fractional part thereof charged for such trans­portation, to be paid by the consignor.
No such parcel or package shall be transported until a stamp or stamps representing the tax due shall have been affixed thereto.

This tax was paid for by the 1917 red documentaries.