Por que não tenho fiação de aterramento em nenhuma das minhas tomadas?

Your house is wired using the EMT conduit wiring method. Individual wires are carried inside metal conduit. The conduit is the ground path. Most commercial and industrial buildings look exactly like this.

Since they are individual wires, they are able to use any of 11 wire colors to disambiguate circuits, instead of the usual black white red. If you wish to add wires, you'd buy THWN-2 wires, stranded is more flexible but more tricky to put on screws.

Switches do not need any further attention to grounding.

Lamps and receptacles may need further attention. Look closely at how the jugo (metal frame, notably the top and bottom ears) make contact with the steel box. If all this is true:

• There is hard face-contact between the yoke and the metal box directly; the yoke is não floating out proud of the metal box connected only by screw threads, and
• The yoke and metal box are not contaminated by paint, rust or other detritus, and
• There is not any little little paper/plastic square that would capture the yoke screws,

then this clean hard-flush contact is an acceptable ground path.

If any of this is insufficient, you must ground the receptacle to the box. Somewhere in the back of the box will be a hole slightly different than the others. It is tapped #10-32 for a ground machine screw (bolt). You can use any 10-32 bolt (machine screw). They sell cute green 10-32 bolts in the hardware store, with or without pigtails pre-attached. Those are perfect.

Metal conduit is an excellent wiring method, and I use it whenever I can. You can use existing conduit routes to add circuits (up to 4 per conduit), so it makes it easy to customize your wiring. For instance if you keep tripping breakers in the kitchen, just throw another circuit in alongside the existing one. Even if you're extending, you can use existing conduit for the homerun - there's no need to bust up any more drywall than you absolutely have to.

AFCIs were originally invented for problem appliances (one in particular: electric blankets). But they were found to protect all sorts of "NM cable, plastic box, lazy installation" type problems tossirbackstabstossir, so AFCIs are now required on almost every circuit. EMT doesn't have those problems, so I don't install AFCI on circuits in metal conduit. (except bedrooms, obviously).

Your pictures appear to show metallic conduit carrying the wires to your boxes. The conduit is also an NEC approved grounding path, so no separate grounding wire is required for the distribution. This evidently is not the case in some other countries.

Current best practice (and code, so far as I recall) is to attach a grounding pigtail from the box (there is normally a raised bump with a threaded hole for this exact purpose) to the device, rather than depending on the mounting screws as a grounding means.

If your house was built in 1989, it would have needed to have ground wires in all of the outlets. The requirement went into effect in the 1968 NEC. Now if your house was built in 1969 (20 years earlier), it might be that in your state, the 1968 NEC was not yet adopted. Some states take a while to adopt changed to the NEC. But not 20 years...

Grounding is a safety issue, but because it is a MANDATORY safety issue, many electronic devices rely upon that solid ground connection to eliminate electrical noise (or give it an easy path to ground). If you have 3 prong outlets but the ground wire is not connected, you have no grounding so not only is it less safe, it is also likely unhealthy for some of your electronics. In a nutshell if your device has a 3 prong plug, it probably NEEDS the ground connection, if it has a 2 prong plug, it doesn't.

A GFCI by the way does NOT "fix" that issue, it just looks at the current flow coming in and going back, and if they are not the same (ostensibly because something is going to ground) it opens the circuit.