The tables are based on ASTM minimums as far as I remember. This is well below the level of units manufactured currently since it is more costly to make a weak unit.
"b. Provisions for this table are based on construction requirements specified in Section 1805.5.2.2."
"1805.5.2.2 Masonry foundation walls. Masonry foundation walls shall comply with the following:
1. Vertical reinforcement shall have a minimum yield strength of 60,000 psi (414 MPa).
2. The specified location of the reinforcement shall equal or exceed the effective depth distance, d, noted in Tables 1805.5(2), 1805.5(3) and 1805.5(4) and shall be measured from the face of the exterior (soil) side of the wall to the center of the vertical reinforcement. The reinforcement shall be placed within the tolerances specified in ACI530.1/ASCE 6/TMS 402, Article 3.4 B7 of the specified location.
3. Grout shall comply with Section 2103.12.
4. Concrete masonry units shall comply with ASTM C 90.
5. Clay masonry units shall comply with ASTM C 652 for hollow brick, except compliance with ASTM C 62 or ASTM C 216 is permitted when solid masonry units are installed in accordance with Table 1805.5(1) for plain masonry.
6. Masonry units shall be installed with Type M or S mortar in accordance with Section 2103.8.
7. The unfactored axial load per linear foot of wall shall not exceed 1.2 tf 'm where t is the specified well thickness in inches and f 'm is the specified compressive strength of masonry in pounds per square inch."
"2103.12 Grout. Grout shall conform to Table 2103.12 or to ASTM C 476. When grout conforms to ASTM C 476, the grout shall be specified by proportion requirements or property requirements."
