Certain shipping options are only available under 2kg.
Contrary to the "economies of scale" theory, smaller parcels can be cheaper. I think it's because they can slip through customs, which does not only save you a headache, it also saves the agent and shipping service time and money; savings they can pass down to you.
There might be more factors in play, but the why doesn't really matter, just look at the potential savings. Take Germany for example:
- 4kg Parcel (Europe Tariffless, Wegobuy): $110 = $28/kg (10-15 days)
- 2kg Parcel (PD EUB, Wegobuy): $32 = $16/kg (10-15 days)
The 2kg parcel is 40% cheaper.
For other European nations, like France, the picture is very similar. That's because these countries have strict customs. The only downside is the small size and how you have to split your hauls.
For non-EU countries with very relaxed customs, economies of scale apply, and the small-parcel-strategy is not worth considering.
added: 6/26/2023