Runway Aiming Point Markings are not found on all runways because the requirement is based on the aerodrome code number and they are not required in all cases.
Aerodrome Reference Code from the ICAO Annex 14 Volume I:
The reference also states:
220.127.116.11 An aiming point marking shall be provided at each approach end of a paved instrument runway where the code number is 2, 3 or 4.
18.104.22.168 Recommendation.– An aiming point marking should be provided at each approach end of:
a) a paved non-instrument runway where the code number is 3 or 4;
b) a paved instrument runway where the code number is 1; when additional conspicuity of the aiming point is desirable.
Sources: ICAO Annex 14 Volume I