To my understanding primary healthcare is not so complex, it is rather simple. All of us understand this and know what is missing. The politics around has been made very complex though. We may get frustrated but WHO in partnership with Gates foundation is very clear what it means by UHC and PHC.
Following was WHO News on 23rd September 2019
WHO welcomes landmark UN declaration
Today world leaders adopted a high-level United Nations Political Declaration on universal health coverage (UHC), the most comprehensive set of health commitments ever adopted at this level. “This declaration represents a landmark for global health and development,” said Dr Tedros Adhanom Ghebreyesus, Director-General at WHO. “The world has 11 years left to make good on its sustainable development goals. Universal health coverage is key to ensuring that happens.” He added: “Universal health coverage is a political choice: today world leaders have signaled their readiness to make that choice. I congratulate them.” The declaration comes the day after the World Health Organization (WHO) and partners flagged the need to double health coverage between now and 2030 or leave up to 5 billion people unable to access health care. In adopting the declaration, U.N. Member States have committed to advance towards UHC by investing in four major areas around primary health care. These include mechanisms to ensure no one suffers financial hardship because they have had to pay for healthcare out of their own pockets and implementing high-impact health interventions to combat diseases and protect women’s and children’s health. In addition, countries must strengthen health workforce and infrastructure and reinforce governance capacity. They will report back on their progress to the U.N. General Assembly in 2023. “Now that the world has committed to health for all, it is time to get down to the hard work of turning those commitments into results,” said Melinda Gates, Co-Chair of the Bill & Melinda Gates Foundation. “We all have a role to play. Donors and country governments need to move beyond business as usual to bolster the primary health care systems that address the vast majority of people’s needs over their lifetimes,” said Gates. On 24 September, WHO and 11 other multilateral organizations, which collectively channel one third of development assistance for health, will launch their Global Action Plan for health and wellbeing for all. The plan will ensure the 12 partners provide more streamlined support to countries to help deliver universal health coverage and achieve the health-related SDG targets
Also What is UHC and What it is not has been clearly defined in below article by WHO published on 24th September 2019 
From this article we find UHC measurement tools which are following

WHO uses 16 essential health services in 4 categories as indicators of the level and equity of coverage in countries:

Reproductive, maternal, newborn and child health:

  • family planning
  • antenatal and delivery care
  • full child immunization
  • health-seeking behaviour for pneumonia.

Infectious diseases:

  • tuberculosis treatment
  • HIV antiretroviral treatment
  • Hepatitis treatment
  • use of insecticide-treated bed nets for malaria prevention
  • adequate sanitation.

Noncommunicable diseases:

  • prevention and treatment of raised blood pressure
  • prevention and treatment of raised blood glucose
  • cervical cancer screening
  • tobacco (non-)smoking.

Service capacity and access:

  • basic hospital access
  • health worker density
  • access to essential medicines
  • health security: compliance with the International Health Regulations.

Each country is unique, and each country may focus on different areas, or develop their own ways of measuring progress towards UHC. But there is also value in a global approach that uses standardized measures that are internationally recognized so that they are comparable across borders and over time.

What comes out is following
UHC is a package of essential (selective primary care)
It is for developing economies
Donors have a role (agenda/ priority setting)
Financial responsibilities rests with the respective participating governments (globalization)
Priorities are
Family planning  (population control)
Tuberculosis ( firefighting)
Anti retroviral treatment (more AIDS Acts and ensuring life long legal obligation of drug provision on governments)
Strategic purchase essential medicines and consumables by the participating governments (whom UHC is meant for ) rather then selling in open market to individuals.
Continued mode of fragmented national health programs and double burden of UHC on the participating government.
11 years are left to be achieved (It has been 20 years since Healthcare for All 2000).
Lip service to health as a right but defining health as a complex entity and simplifying it into – tuberculosis and AIDS for UHC purpose.
Some what it looks very haphazard but it is very clear in its intent and well crafted word to word. Why do we have confusion? It is simple and very clear. 
Best wishes
Raman Kumar