It's simple, because many think that pharma make their own raws, which is absolutely false, most of western pharma import their raws from China, and most of pharmaceutical labs cannot afford organic synthesis costs done locally.
Pharma are just like UGL with importation permissions, so they do not have to deal with legal issues and customs, they have often more quality check than UGL, but it's same same, all from Chinese factories.
We do offer most of pharma products: antibiotics, paracetamol, antidepressants, heart burn drugs, pain killers, diarrhea traitement, hiv, all what you can find or imagine in your local pharma store.
Same for universities, and research labs, they do purchase from China all their materials, with research import permission, examples:
Preparation, characterization, dissolution, and permeation of flibanserin − 2-HP-β-cyclodextrin inclusion complexes
"FLB was purchased from Qingdao Sigma Chemical Co., Ltd. (Qingdao, China). "
https://www.ejmcm.com/article_3304_99d83089286120c2761495e38c7977a0.pdf
"The major chemicals were purchased from Qingdao Sigma Chemical Co., Ltd. All commercially available reagents were used without further purification."
2.1. Materials —Bio-101
"Raloxifene hydrochloride (RLX) was from Qingdao Sigma Chemical Co., Ltd., Qingdao, China. "
https://ur.booksc.eu/book/81316686/1cba06
"Bovine pepsin was purchased from Qingdao Sigma Chemical Co., Ltd."
https://pubs.acs.org/doi/10.1021/acs.iecr.0c02005
"Sesbania powder (SP) was commercially supplied from Qingdao Sigma Chemical Co., Ltd. (Qingdao, China)"
Oral gel loaded with penciclovir–lavender oil nanoemulsion to enhance bioavailability and alleviate pain associated with herpes labialis
"PV was obtained as a gift sample from Qingdao Sigma Chemical Co., Ltd. Shandong, China."
"Oregano oil was gifted by Qingdao Sigma Chemical Co., Ltd., Shandong, China."
ACNP 60th Annual Meeting: Poster Abstracts P276 – P550
"A 30 mg/kg solution of TIA NaCl (Qingdao Sigma Chemical Co., purity verified by NMR analysis) was delivered at a dose of 0.1 ml/10 grams mouse weight via intraperitoneal injection twice per day for 14 days. "
https://www.mdpi.com/1999-4923/13/12/2150/pdf
"Minoxidil was gifted by Qingdao Sigma Chemical Co., Ltd. (Qingdao, China)."