Looking at the Builder trait (which works):
<Stats>
<EffectType>Mining</EffectType>
<Scope>Global</Scope>
<Target>
<TargetType>StrategicResource</TargetType>
</Target>
<BonusType>Flat</BonusType>
<Value>2</Value>
</Stats>
The Tech is:
<Stats>
<EffectType>Mining</EffectType>
<Target>
<TargetType>StrategicResource</TargetType>
</Target>
<BonusType>Flat</BonusType>
<Value>1</Value>
</Stats>
If it's meant to work the same way (+1 for each mined), then there should be a <Scope>Global</Scope>