Hope to find you well and in good spirits today.
I think what you are referring to is, Service Equipment Grounding.
An acceptable grounding electrode system would include [250-50]:
A: Underground metal piping electrically continuous for a minimum of 10 feet supplemented with ground rods.
B: Effectively grounded metal frame of a building.
C: Bare, galvanized, or other electrically conductive coating, reinforcing steel rods not smaller than 1/2 inch in diameter if the total length of the steel is not less than 20 feet.
D: Ground ring encircling the building or structure in direct contact with the earth at a depth below the earth’s surface of not less than 2 1/2 feet consisting of at least 20 feet of bare copper conductor not smaller than No. 2.
Neutral-to-Ground Connection - Section 250-24(a)(1)
If you can not see the GEC,it becomes a ‘limitation’ visually. No worries. BUT. Use a tool to measure the presence of ground. Three bulb receptacle tester or circuit analyzer.
Your assumption, “I assume its grounded in the meter but should there be a GEC from the grounding bus to the meter or does the neutral serve that purpose” can be answered here.
Since the neutral or ground conductor is a necessary part of the electrical path, ground/ed conductors carry electrical current under normal operating conditions. Grounding conductors provide an alternate path for the current to flow back to the source, rather than go through anyone touching a dangerous appliance or electrical box.
Hope that helps/helped/assisted your inquiry.