Why are starships built so light ?

[Old vet]

Starfinder dreadnought
15,000 feet and over
8000 plus tons

So you can go as light as 1000lbs per foot

WWII Naval dreadnoughts with their heavy amour and massive guns have a much different tonnage.

Iowa standard displacement 45,000 tons, length 887 feet
Yamato standard displacement 71,000 tons length 862 feet

The average cruise ship weighs from 20,000 to 60,000 tons, though cruise ship weights are usually calculated using gross registered tons. One GRT is equal to 100 cubic feet of enclosed revenue-earning space within the ship. On the GRT scale, modern cruise ships have an average weight of 100,000 GRT.

In my opinion most of the length & tonnage table needs to reworked
A new table would allow for new classes such as: Scout
escort/cutter
frigate
Light Cruiser
Heavy Cruiser
Super Dreadnought
Titan
Legendary, only built by the largest empires

At the small end of the size scale the fighters are fine

Starfinder tiny 3-20 tons F16 unfueled 10 tons F15 unfueled 20 tons

But why stop at three tons

There should be a smaller micro class (1-3 tons) for escape pods, work pods, un crewed probes and message pods ect.
no deck plans, strap in designs
a micro power core, pure battery or solar cells (with a battery)

The Mercury capsule was only 1.5 tons

You need to keep a secret, blast the message pod
Can't let evil escape, tractor the escape pods
Play it out on space map if a rescue ship or some other situation could give the micro ship a chance to get away.

[The Artificer]

Generally speaking anything over 300whatever is a completely made up number that was arbitrarily chosen at the time because it looked big. lots of things have this going on in this game ie populations of planets.

If it isn't in Bulk it usually doesn't matter to the players anyway.

Edit

I still respect your enthusiastic elevation, lots of people on this forum have brought this up before.

[Garretmander]

Because sci-fi writers have no sense of scale

[BigNorseWolf]

Take a look at the suggested critter weights.

Square cubed law doesn't seem to be well understood in general.

[John Compton]

This is a known issue. Earlier this week, I submitted adjusted weights to appear in the Starfinder Core Rulebook Pocket Edition and future printings.

[Thrice Great Hermes]

The ships are all built out of materials that are much lighter and stronger for their weight.

Than anything that we have access to now, perhaps with exception of some highly experimental and not yet released to the public material.

[Peg'giz]

The starship system has a lot of problems, this one is one of the lesser one (since ship weight doesn't really play a role ingame).