siege tanks on their own aren’t much of a threat or a problem.
they are available Very early into the game, requiring only a factory with tech lab.
most terran players will add atleast one siege tank to their defences even if they aren’t planning on using mech - or providing any upgrades for the tank.
a lone siege tank is just that effective - and will typically earn back at least 10x its value (on a bad day)
once they transition into siege mode they have the longest range in the game and provide tremendous splash damage. siege tanks will typically be positioned behind terran supply walls, a planetary fortress - or behind walls of hellbats, thors, marines & medivacs.
this strategy is effectively rendering nearly all zerg ground forces to be useless.
because zerg forces have such low health, low range - and naturally travel in such large numbers - these siege tank hits are absolutely catastrophic.
roaches, ravagers, hydra, zergling, baneling are all units that require large numbers to perform well or over power the opponent, however siege tanks are providing so many free splash kills from outside of zerg’s range, that using troops like these just results in as many dead zerg as you throw at the siege tank.
since siege tank are so easily available - and are a part of nearly every terran build order, zerg needs to accept that his ground units are Never going to be able to push into terran siege tanks -and must find another solution.
However the problem, is there is no real solution. Infestors & ravagers are outranged by siege tanks forcing zerg to make some kind of sacrrifice in order to successfully perform an ability. This leaves swarm hosts as the only true unit suited to fighting siege tanks. however swarm hosts require so much supply to be effective you are forced to devote a huge portion of your army into killing what could only be 1 unupgraded siege tank.
vipers & Broodlords would be a better option, but since they are an extremely late game unit this isn’t an option for dealing with a lone siege tank behind a wall in the early game.
the biggest weakness with siegetanks is air units - but terrans basic marines provide Anti air. Mutalisks, locust swarms, vipers & brood lords can all be potentially faught off by what will be an army of marines & thors.
marines & thors counter mutalisks so badly that zerg MUST keep mutalisks away at all times, making it Essential to misdirect the terran opponent in order to get any damage done.
comparing siege tanks directly to lurkers - siege tanks are available much faster & are less expensive - siege tanks are available without specifically focusing on any army composition - lurkers require you to go off specifically into lurker tech.
siege tanks require no specific upgrades. lurkers have 2 specific upgrades to increase range and burrow speed in order to even begin to compete with siege tanks.
lurkers have less range, and cannot attack when unburrowed.
siege tanks have more range, and can attack when unsieged.
every zerg ground unit can burrow.
terran has orbital scans nearly by default to always provide detection.
zerg needs to specifically decide to create overseers in order to gain detection.